KR102022143B1 - Ultrasound system and method for adaptively compensating spectral downshift of signals - Google Patents

Ultrasound system and method for adaptively compensating spectral downshift of signals Download PDF

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KR102022143B1
KR102022143B1 KR1020150185721A KR20150185721A KR102022143B1 KR 102022143 B1 KR102022143 B1 KR 102022143B1 KR 1020150185721 A KR1020150185721 A KR 1020150185721A KR 20150185721 A KR20150185721 A KR 20150185721A KR 102022143 B1 KR102022143 B1 KR 102022143B1
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phase
phase shift
pass filter
bandwidth
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최동영
이동준
이유화
이상신
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지멘스 메디컬 솔루션즈 유에스에이, 인크.
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Abstract

An ultrasound system and method for adaptively compensating for spectral downshift of a signal is disclosed. The ultrasound system includes an ultrasound probe and a processor. The ultrasound probe transmits an ultrasound signal to the object and receives an ultrasound echo signal from the object. The processor forms a complex baseband signal comprising the same phase component signal and a quadrature phase component signal based on the ultrasonic echo signal, determines the phase shift and phase dispersion based on the complex baseband signal, and determines the phase shift and phase dispersion. The demodulated baseband signal is filtered by a dynamic filter to adaptively compensate for the spectral downshift of the ultrasonic echo signal.

Description

ULTRASOUND SYSTEM AND METHOD FOR ADAPTIVELY COMPENSATING SPECTRAL DOWNSHIFT OF SIGNALS

TECHNICAL FIELD The present disclosure relates to ultrasonic systems, and more particularly, to ultrasonic systems and methods for adaptively compensating for spectral downshift of a signal.

Ultrasound systems are widely used in the medical field to obtain information about objects of interest within an object. The ultrasound system may provide high resolution images of the subject in real time using high frequency sound waves, without the need for a surgical operation to directly incision the subject. Ultrasound systems have non-invasive and nondestructive properties and are widely used in the medical field.

The ultrasound system transmits an ultrasound signal to the object and receives an ultrasound signal (ie, an ultrasound echo signal) reflected from the object. In addition, the ultrasound system performs a beamforming process on the ultrasonic echo signal to form a received focus signal, performs a quadrature demodulation on the received focused signal to form a complex baseband signal, and complex complex An ultrasound image of the object is formed based on the band signal.

In general, when an ultrasound signal propagates to an object, the ultrasound signal is attenuated by the medium of the object. Due to the attenuation of the ultrasonic signal, a spectral (frequency) downshift occurs in the ultrasonic echo signal reflected from the medium of the object. Spectral downshift of the ultrasonic echo signal degrades the performance of orthogonal demodulation and degrades the image quality of the ultrasonic image.

To compensate for the spectral downshift of the ultrasonic echo signal, dynamic quadrature demodulation is used which dynamically adjusts the demodulation frequency and the cutoff frequency of the filter. However, dynamic orthogonal demodulation compensates for the spectral downshift of the ultrasound echo signal under the assumption that the medium in the object is uniform and the attenuation coefficients of the ultrasound echo signal are the same. Therefore, the dynamic orthogonal demodulation compensates for the spectral downshift even for the ultrasonic echo signal of the medium having a non-constant attenuation coefficient, thereby degrading the quality of the ultrasonic image.

The present disclosure provides an ultrasound system and method for forming a complex baseband signal based on an ultrasound echo signal from an object, and adaptively compensating for spectral downshift of the ultrasound echo signal based on the complex baseband signal.

In one embodiment, the ultrasound system includes an ultrasound probe and a processor. The ultrasound probe is configured to transmit an ultrasound signal to the object and receive an ultrasound echo signal from the object. The processor forms a complex baseband signal comprising the same phase component signal and a quadrature phase component signal based on the ultrasonic echo signal, determines the phase shift and phase dispersion based on the complex baseband signal, and determines the phase shift and phase dispersion. And filter the complex baseband signal by a dynamic filter to adaptively compensate for the spectral downshift of the ultrasonic echo signal based on that.

In another embodiment, a method for adaptively compensating for spectral downshift includes transmitting an ultrasound signal to an object and receiving an ultrasound echo signal from the object, and in-phase component signal and quadrature based on the ultrasound echo signal. Forming a complex baseband signal comprising a phase component signal, determining a phase shift and phase dispersion based on the complex baseband signal, and spectrally down the ultrasonic echo signal based on phase shift and phase dispersion Filtering the complex baseband signal by a dynamic filter to adaptively compensate for the shift.

According to the present disclosure, it is possible to determine (predict) the phase shift and the phase dispersion based on the ultrasonic echo signal of the object, and adaptively compensate for the spectral downshift of the ultrasonic echo signal based on the determined phase shift and the phase dispersion. Can be. Therefore, the image quality of the ultrasound image may be prevented from changing according to the attenuation coefficient of the medium in the object.

1 is a block diagram schematically showing the configuration of an ultrasound system according to an embodiment of the present disclosure.
2 is a block diagram schematically illustrating a configuration of a processor according to an embodiment of the present disclosure.
3 is a block diagram schematically illustrating a configuration of a signal processing unit according to a first embodiment of the present disclosure.
4 is a block diagram schematically illustrating a configuration of a complex baseband signal forming unit according to a first embodiment of the present disclosure.
5 shows examples of phase shift, phase dispersion, smoothed phase shift and smoothed phase dispersion in accordance with a first embodiment of the present disclosure;
6 is a block diagram schematically illustrating a configuration of a signal processing unit according to a second embodiment of the present disclosure.
7 is a block diagram schematically illustrating a configuration of an upmixing processing unit according to a second embodiment of the present disclosure.

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. As used herein, the term "unit" refers to software or hardware components such as software, field-programmable gate arrays (FPGAs), and application specific integrated circuits (ASICs). However, "part" is not limited to hardware and software. The "unit" may be configured to be in an addressable storage medium, and may be configured to play one or more processors. Thus, as an example, "parts" means components such as software components, object-oriented software components, class components, and task components, and processors, functions, properties, procedures, subroutines, program code. Includes segments, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. Functions provided within components and "parts" may be combined into a smaller number of components and "parts" or further separated into additional components and "parts".

1 is a block diagram schematically showing the configuration of an ultrasound system 100 according to an embodiment of the present disclosure. The ultrasound system 100 includes a control panel 110, an ultrasound probe 120, a processor 130, a storage 140, and a display 150. In one embodiment, the processor 130 controls the control panel 110, the ultrasonic probe 120, the storage 140, and the display 150.

The control panel 110 receives input information from a user and transmits the received input information to the processor 130. The control panel 110 may include an input device (not shown) that enables an interface between the user and the ultrasound system 100 and enables the user to operate the ultrasound system 100. The input device may include an input unit suitable for performing an operation such as selecting a diagnostic mode, controlling a diagnostic operation, inputting an appropriate command required for diagnosis, signal manipulation, output control, and the like, for example, a trackball, a keyboard, a button, and the like.

The ultrasonic probe 120 includes an ultrasonic transducer (not shown) configured to mutually convert an electrical signal and an ultrasonic signal. The ultrasound probe 120 transmits an ultrasound signal to an object (not shown). The subject includes an object of interest (eg, liver, heart, etc.). In addition, the ultrasound probe 120 receives an ultrasound signal (ie, an ultrasound echo signal) reflected from the object and converts the ultrasound echo signal into an electrical signal (hereinafter, referred to as a "receive signal").

The processor 130 controls the ultrasound probe 120 to transmit an ultrasound signal to the object and to receive an ultrasound echo signal reflected from the object in response to the input information received through the control panel 110. In addition, the processor 130 forms ultrasonic data based on the received signal provided from the ultrasonic probe 120. In addition, the processor 130 forms an ultrasound image (eg, a B mode image) of the object based on the ultrasound data.

The storage 140 sequentially stores the received signal formed by the ultrasonic probe 120 for each frame. In addition, the storage 140 sequentially stores the ultrasound data formed by the processor 130. In addition, the storage 140 stores one or more ultrasound images formed by the processor 130. In addition, the storage 140 may store instructions for operating the ultrasound system 100.

The display unit 150 displays one or more ultrasound images formed by the processor 130. In addition, the display unit 150 may display suitable information about the ultrasound image or the ultrasound system 100.

2 is a block diagram schematically illustrating a configuration of a processor 130 according to an embodiment of the present disclosure. The processor 130 includes a transmitter 210. The transmitter 210 forms an electrical signal (hereinafter, referred to as a “transmission signal”) for obtaining an ultrasound image of the object. For example, the transmission signal has a preset frequency. The transmission signal is provided to the ultrasonic probe 120. The ultrasound probe 120 converts the transmission signal into an ultrasound signal and transmits the converted ultrasound signal to the object. In addition, the ultrasound probe 120 receives the ultrasound echo signal reflected from the object to form a received signal.

The processor 130 further includes a transmit / receive switch 220 and a receiver 230. The transmission and reception switch 220 serves as a duplexer for switching between the transmitter 210 and the receiver 230. For example, when the ultrasound probe 120 alternately transmits and receives the transmit / receive switch 220, the transmitter / receiver 220 may properly transmit the transmitter 210 or the receiver 230 to the ultrasound probe 120 (that is, the ultrasound transducer). Operate to switch or electrically connect.

The receiver 230 amplifies the received signal provided from the ultrasound probe 120 through the transmission / reception switch 230 and converts the amplified received signal into a digital signal. The receiver 230 includes a time gain compensation (TGC) unit (not shown) for compensating for attenuation normally occurring while the ultrasonic signal passes through the object, and an analog-to-digital conversion for converting an analog signal into a digital signal. (analog to digital conversion) unit (not shown) and the like.

The processor 130 further includes a signal forming unit 240. The signal forming unit 240 performs a beam forming process on the digital signal provided from the receiving unit 230 to form a receiving focus signal. The reception focus signal may be a radio frequency (RF) signal, but is not limited thereto.

The processor 130 further includes a signal processor 250. The signal processor 250 forms complex baseband signals based on the received focus signal provided from the signal generator 240. In addition, the signal processor 250 determines the phase shift and phase dispersion based on the complex baseband signal, and adapts the spectral downshift of the received focus signal (ie, the ultrasonic echo signal) based on the determined phase shift and phase dispersion. Form a dynamic filter to compensate. In addition, the signal processor 250 filters the complex baseband signal by using the formed dynamic filter.

The processor 130 further includes an image forming unit 260. The image forming unit 260 forms an ultrasound image of the object based on the complex baseband signal filtered by the signal processing unit 250.

3 is a block diagram schematically illustrating a configuration of the signal processor 250 according to the first embodiment of the present disclosure. The signal processor 250 includes a complex baseband signal forming unit 310. The complex baseband signal forming unit 310 forms a complex baseband signal based on the received focus signal provided from the signal forming unit 240. For example, the complex baseband signal includes an in-phase component signal (I signal) and a quadrature phase component signal (Q signal).

4 is a block diagram schematically illustrating a configuration of the complex baseband signal forming unit 310 according to the first embodiment of the present disclosure. The complex baseband signal forming unit 310 includes an orthogonal demodulation unit 410.

The quadrature demodulator 410 performs orthogonal demodulation on the received focus signal provided from the signal generator 240 to form the same phase component signal and the quadrature phase component signal. In one embodiment, orthogonal demodulator 410 includes a cosine function multiplier 411 and a sine function enhancer 412. The cosine function multiplier 411 multiplies the cosine function cos2 pi f T n by the received focus signal to form an in-phase component signal. For example, the frequency f T of the cosine function cos2πf T n may be the frequency of the transmission signal formed by the transmitter 210. The sine function multiplier 412 multiplies the sine function sin2πf T n by the received focus signal to form a quadrature phase component signal. For example, the frequency f T of the sine function sin2πf T n may be the frequency of the transmission signal formed by the transmitter 210.

The complex baseband signal forming unit 310 further includes a low pass filtering unit 420. The low pass filtering unit 420 is connected to the orthogonal demodulator 410 to filter the in-phase and quadrature phase component signals provided from the orthogonal demodulator 410. In one embodiment, the low pass filtering unit 420 includes a first low pass filter 421 and a second low pass filter 422. The first low pass filter 421 is coupled to the cosine function multiplier 411 to filter the in-phase component signal provided from the cosine function multiplier 411. For example, the cutoff frequency f c of the first low pass filter 421 may be a frequency f T of the transmission signal formed by the transmitter 210. A second low pass filter 422 is coupled to sine function multiplier 412 to filter the orthogonal transform signal provided from sine function multiplier 412. For example, the cutoff frequency f c of the second low pass filter 422 may be a frequency f T of the transmission signal formed by the transmitter 210.

The complex baseband signal forming unit 310 further includes a decimation unit 430. The decimation unit 430 is connected to the low pass filtering unit 420 to decimate the in-phase and quadrature phase component signals filtered by the low pass filtering unit 420 based on a preset sampling frequency. Perform the process. In one embodiment, the decimation unit 430 includes a first decimation unit 431 and a second decimation unit 432. The first decimation unit 431 is connected to the first low pass filter 421 to perform decimation on the same phase component signal filtered by the first low pass filter 421. The second decimation unit 432 is connected to the second low pass filter 422 to perform decimation on the quadrature phase component signal filtered by the second low pass filter 422.

Referring back to FIG. 3, the signal processor 250 further includes a signal converter 320. The signal converter 320 performs Fourier transform on the complex baseband signal provided from the complex baseband signal forming unit 310. For example, the Fourier transform includes a short-time Fourier transform (STFT). In one embodiment, the signal converter 320 divides the complex baseband signal into a plurality of regions by applying a window having a predetermined size to the complex baseband signal provided from the complex baseband signal forming unit 310. . In addition, the signal converter 320 performs a Fourier transform on the complex baseband signal corresponding to each region to form a Fourier transform signal.

The signal processor 250 further includes a phase information determiner 330. The phase information determiner 330 determines phase information based on a Fourier transform signal provided from the signal converter 320. For example, phase information includes phase shift and phase dispersion.

According to an exemplary embodiment, the phase information determiner 330 may perform phase shifts Δφ i, based on Fourier transform signals corresponding to each of the plurality of regions m × n, as illustrated in FIG. 5A . j (1 ≦ i ≦ m, 1 ≦ j ≦ n) is determined. For example, the phase shift can be determined by the following equation.

Figure 112016028333404-pat00001

Here, Δφ represents a phase shift, Im {} represents an imaginary part of a signal (for example, a Fourier transform signal), Re {} represents a real part of a signal (for example, a Fourier transform signal), and R (1 ) Represents one-lag autocorrelation.

In addition, as illustrated in FIG. 5A, the phase information determiner 330 based on the Fourier transform signal corresponding to each of the plurality of regions m × n has a phase dispersion σ 2 i, j (1 ≤ i ≤ m, 1 ≤ j ≤ n)). For example, the phase variance can be determined by the following equation.

Figure 112016028333404-pat00002

Here, σ 2 represents phase dispersion, R (0) represents zero-lag autocorrelation, and R (1) represents original lag autocorrelation.

The signal processor 250 further includes a spatial filter 340. The spatial filtering unit 340 performs a smoothing process on the phase information determined by the phase information determining unit 330 (ie, phase shift and phase dispersion). For example, the spatial filter 340 includes a spatial filter (not shown) for performing the smoothing process.

In one embodiment, the spatial filtering unit 340 is a phase shift (Δφ i, j (1 ≦ i ≦ m, 1 ≦ j ≦ n)) by a spatial filter, as shown in FIG. Smoothed by shifting the phase shift to (

Figure 112016028333404-pat00003
(1 ≦ i ≦ m, 1 ≦ j ≦ n)). In addition, the spatial filtering unit 340 smoothes the phase dispersion (σ 2 i, j (1 ≦ i ≦ m, 1 ≦ j ≦ n)) by the spatial filter as shown in FIG. To perform smoothed phase dispersion (
Figure 112016028333404-pat00004
(1 ≦ i ≦ m, 1 ≦ j ≦ n)).

The signal processor 250 further includes a dynamic filter 350. The dynamic filtering unit 350 filters the Fourier transform signal provided from the signal conversion unit 320 based on the phase information determined by the spatial filtering unit 340 (that is, the smoothed phase shift and phase dispersion). For example, the dynamic filtering unit 350 includes a dynamic filter (ie, band pass filter, not shown) for adaptively compensating for spectral downshift of the reception focus signal (ie, ultrasonic echo signal).

In one embodiment, the dynamic filtering unit 350 is smoothed phase dispersion (

Figure 112016028333404-pat00005
Based on (1 ≦ i ≦ m, 1 ≦ j ≦ n), the bandwidth of the dynamic filter (i.e., band pass filter) is determined. For example, the bandwidth of the band pass filter can be determined according to the following equation.

Figure 112016028333404-pat00006

Where B represents the bandwidth of the band pass filter,

Figure 112016028333404-pat00007
Denotes the smoothed phase dispersion.

In addition, the dynamic filtering unit 350 determines the determined bandwidth (B) and smoothed phase shift (

Figure 112016028333404-pat00008
The cutoff frequency of the bandpass filter is determined based on (1 ≦ i ≦ m, 1 ≦ j ≦ n). For example, the cutoff frequency of the band pass filter may be determined according to the following equation.

Figure 112016028333404-pat00009

Where ω c represents the cutoff frequency of the band pass filter, B represents the bandwidth of the band pass filter,

Figure 112016028333404-pat00010
Represents the smoothed phase shift,
Figure 112016028333404-pat00011
Denotes the smoothed phase dispersion.

The dynamic filtering unit 350 forms a dynamic filter (that is, a band pass filter) based on the determined bandwidth B and the cutoff frequency ω c , and provides a Fourier provided from the signal converter 320 by the formed dynamic filter. Filter the conversion signal.

The signal processor 250 further includes a signal inverse converter 360. The inverse transform unit 360 performs an inverse Fourier transform on the Fourier transform signal filtered by the dynamic filtering unit 350 to form a complex baseband signal (ie, an in-phase component signal and a quadrature phase component) in the time domain. do.

6 is a block diagram schematically illustrating a configuration of a signal processor 250 according to a second embodiment of the present disclosure. The signal processor 250 includes a complex baseband signal forming unit 610. Since the complex baseband signal forming unit 510 in this embodiment is the same as the complex baseband signal forming unit 310 in the first embodiment, the description of the complex baseband signal forming unit 610 is omitted.

The signal processor 250 further includes a phase information determiner 620. The phase information determiner 620 determines phase information based on the complex baseband signal provided from the complex baseband signal forming unit 610. For example, phase information includes phase shift and phase dispersion.

In one embodiment, the phase information determiner 620 divides the complex baseband signal into a plurality of regions (for example, m × n) by applying a window having a predetermined size to the complex baseband signal. The phase information determiner 620, based on the complex baseband signal corresponding to each region, as shown in Fig. 5A shows a phase shift Δφ i, j (1 ≦ i ≦ m, 1 ≦ j ≦ n)). For example, the phase shift may be determined according to Equation 1 described above.

In addition, the phase information determiner 620 based on the complex baseband signal corresponding to each region, as shown in FIG. 5 (b), the phase dispersion (σ 2 i, j (1 ≦ i ≦ m, 1). ≤ j ≤ n)). For example, the phase dispersion may be determined according to Equation 2 described above.

The signal processor 250 further includes a spatial filter 630. Since the spatial filter 630 in the present embodiment is the same as the spatial filter 340 in the first embodiment, description of the spatial filter 630 is omitted.

The signal processor 250 further includes an upmixing unit 640. The upmixer 640 may determine a phase shift determined by the spatial filter 630.

Figure 112016028333404-pat00012
Based on (1 ≦ i ≦ m, 1 ≦ j ≦ n), an upmixing process is performed on the complex baseband signal provided from the complex baseband signal forming unit 610.

7 is a block diagram schematically illustrating a configuration of an upmixing unit 540 according to a second embodiment of the present disclosure. The upmixing unit 640 includes a first upmixing cosine function multiplier 710. The first upmix cosine function multiplier 610 is coupled to the complex baseband signal forming unit 510. The first upmix cosine function multiplier 710 is configured to cosine a function of a complex baseband signal (ie, an in-phase component signal (I signal)) provided from the complex baseband signal forming unit 610.

Figure 112016028333404-pat00013
) To form a first upmix signal. Where the cosine function (
Figure 112016028333404-pat00014
F S at) denotes a sampling frequency at a decimation unit (not shown) of the complex baseband signal forming unit 610.

The upmixing unit 640 further includes a first upmixing sine function multiplier 720. The first upmix sine function multiplier 720 is coupled to the complex baseband signal forming unit 610. The first upmixing sine function multiplier 720 adds a sine function to the complex baseband signal (ie, in-phase component signal (I signal)) provided from the complex baseband signal forming unit 610.

Figure 112016028333404-pat00015
) To form a second upmix signal.

The upmixing unit 640 further includes a second upmixing cosine function multiplier 730. The second upmix cosine function multiplier 730 is coupled to the complex baseband signal forming unit 610. 2 Upmixing cosine function multiplier 730 is a cosine function (i.e., quadrature phase component signal (Q signal)) provided from complex baseband signal forming unit 610.

Figure 112016028333404-pat00016
) To form a third upmix signal.

The upmixing unit 640 further includes a second upmixing sine function multiplier 740. The second upmixing sine function multiplier 740 is coupled to the complex baseband signal forming unit 610. The second upmixing sine function multiplier 740 is a sine function (i.e., a quadrature baseband signal (Q signal) provided from the complex baseband signal forming unit 610).

Figure 112016028333404-pat00017
) To form a fourth upmix signal.

The upmixing unit 640 further includes a first adder 750. The first adder 750 is coupled to the first upmixing cosine function multiplier 710 and the second upmixing sine function multiplier 740. The first adder 750 adds the first upmixing signal provided from the first upmixing cosine function multiplier 710 and the fourth upmixing signal provided from the second upmixing sine function multiplier 740 to form the same phase. Form component signals.

The upmixing unit 640 further includes a second adder 760. The second adder 760 is coupled to the first upmixing sine function multiplier 720 and the second upmixing cosine function multiplier 730. The second adder 760 adds the second upmixing signal provided from the first upmixing sine function multiplier 720 and the third upmixing signal provided from the second upmixing cosine function multiplier 730 to form an orthogonal phase. Form component signals.

Referring back to FIG. 6, the signal processor 250 further includes a dynamic filter 650. The dynamic filtering unit 650 is based on the phase dispersion determined by the spatial filtering unit 630 (ie, smoothed), and the signal up-processed by the upmixing unit 640 (that is, the same phase component signal) I signal) and quadrature phase component signal (Q signal). For example, the dynamic filtering unit 650 may include a dynamic filter (eg, a linear time varying (LTV) low pass filter, for adaptively compensating for spectral downshift of the reception focus signal (ie, ultrasonic echo signal), Not shown).

In one embodiment, the dynamic filtering unit 650 is a first LTV low pass filter (not shown) and a second of the upmixing unit 640 connected to the first adder 750 of the upmixing unit 640. A second LTV low pass filter (not shown) coupled to the adder 760.

In one embodiment, the dynamic filtering unit 650 is smoothed phase dispersion (

Figure 112016028333404-pat00018
Based on (1 ≦ i ≦ m, 1 ≦ j ≦ n), determine the bandwidth of the dynamic filter (ie, LTV low pass filter). For example, the bandwidth of the dynamic filter (ie, LTV low pass filter) can be determined by Equation 3 above.

In addition, the dynamic filtering unit 650 determines the cutoff frequency of the dynamic filter (ie, the LTV low pass filter) based on the determined bandwidth. For example, the cutoff frequency of the dynamic filter may be determined according to the following equation.

Figure 112016028333404-pat00019

Where ω c, LPF represents the cutoff frequency of the LTV low pass filter, B represents the bandwidth of the LTV low pass filter,

Figure 112016028333404-pat00020
Denotes the smoothed phase dispersion.

The dynamic filtering unit 350 forms a dynamic filter (that is, an LTV low pass filter) based on the determined bandwidth B and the cutoff frequency ω c, LPF and from the upmixing unit 640 by the formed dynamic filter. Filter the provided signals (same phase component signal (I signal) and quadrature phase component signal (Q signal).

While specific embodiments have been described, these embodiments are presented by way of example and should not be construed as limiting the scope of the disclosure. The novel methods and apparatus of the present disclosure may be embodied in a variety of other forms and furthermore, various omissions, substitutions and changes in the embodiments disclosed herein are possible without departing from the spirit of the present disclosure. The claims appended hereto and their equivalents should be construed to include all such forms and modifications as fall within the scope and spirit of the disclosure.

100: ultrasonic system 110: control panel
120: ultrasonic probe 130: processor
140: storage unit 150: display unit
210: transmitting unit 220: transmission and reception switch
230: receiving unit 240: signal forming unit
250: signal processor 260: image forming unit
310, 610 complex baseband signal generator
320: signal conversion unit
330 and 620: phase information determiner
340 and 630: spatial filtering unit
350, 650: dynamic filtering unit
360: signal inverse converter
410: orthogonal demodulator
411: cosine function multiplier 412: sine function multiplier
420: Low pass filtering unit 421: First low pass filter
420: second low pass filter 430: decimation unit
431: First decimation unit 432: Second decimation unit
640: upmixing unit
710: First upmix cosine function multiplier
720: first upmixing sine function multiplier
730: second upmix cosine function multiplier
740: second upmixing sine function multiplier
750: first adder 760: second adder

Claims (35)

As an ultrasonic system,
An ultrasound probe configured to transmit an ultrasound signal to an object and receive an ultrasound echo signal from the object;
Form a complex baseband signal comprising an equal phase component signal and a quadrature phase component signal based on the ultrasonic echo signal, determine a phase shift and phase dispersion based on the complex baseband signal, and determine the phase shift and the phase A processor configured to filter the complex baseband signal by a dynamic filter to adaptively compensate for the spectral downshift of the ultrasonic echo signal based on variance
Ultrasound system comprising a. The ultrasonic system of claim 1, wherein the dynamic filter comprises a band pass filter. The method of claim 2, wherein the processor,
A signal converter configured to perform a Fourier transform on the complex baseband signal to form a Fourier transform signal;
A phase information determiner configured to determine the phase shift and the phase dispersion based on the Fourier transform signal;
A spatial filtering unit configured to perform a smoothing process on the phase shift and the phase dispersion;
A dynamic filtering unit configured to form the band pass filter based on the smoothed phase shift and the phase dispersion, and to filter the Fourier transform signal by the band pass filter;
A signal inverse transform unit configured to perform an inverse Fourier transform on the Fourier transform signal filtered by the band pass filter
Ultrasound system comprising a. 4. The ultrasound system of claim 3 wherein the Fourier transform comprises a short-time Fourier transform (STFT). The method of claim 3, wherein the phase shift,
Figure 112016028333404-pat00021
(Mathematical formula)
Calculated by the above equation,
Δφ represents the phase shift, Im {} represents the imaginary part of the Fourier transform signal, Re {} represents the real part of the Fourier transform signal, and R (1) represents one-lag autocorrelation. Indicating ultrasound system. The method of claim 3, wherein the phase dispersion,
Figure 112016028333404-pat00022
(Mathematical formula)
Calculated by the above equation,
σ 2 represents the phase dispersion, R (0) represents zero-lag autocorrelation, and R (1) represents one lag autocorrelation. The method of claim 3, wherein the dynamic filtering unit,
Determine a bandwidth of the band pass filter based on the smoothed phase dispersion,
Determine a cutoff frequency of the bandpass filter based on the bandwidth and the smoothed phase shift,
And form the bandpass filter based on the bandwidth and the cutoff frequency. The method of claim 7, wherein the bandwidth,
Figure 112016028333404-pat00023
(Mathematical formula)
Calculated by the above equation,
B represents the bandwidth,
Figure 112016028333404-pat00024
Is an ultrasonic system representing the smoothed phase dispersion. The method of claim 7, wherein the cutoff frequency is,
Figure 112016028333404-pat00025
(Mathematical formula)
Calculated by the above equation,
ω c represents the cutoff frequency, B represents the bandwidth,
Figure 112016028333404-pat00026
Represents the smoothed phase shift,
Figure 112016028333404-pat00027
Is an ultrasonic system representing the smoothed phase dispersion. The ultrasound system of claim 1 wherein the dynamic filter comprises a linear time varying (LTV) low pass filter. The method of claim 10, wherein the processor,
A phase information determiner configured to determine the phase shift and the phase dispersion based on the complex baseband signal;
A spatial filtering unit configured to perform a smoothing process on the phase shift and the phase dispersion;
An upmixing unit configured to perform an upmixing process on the complex baseband signal based on the smoothed phase shift;
A dynamic filtering unit configured to form the low pass filter based on the smoothed phase dispersion and to filter the complex baseband signal upmixed by the low pass filter
Ultrasound system comprising a. The method of claim 11, wherein the phase shift,
Figure 112016028333404-pat00028
(Mathematical formula)
Calculated by the above equation,
Δφ represents the phase shift, Im {} represents the imaginary part of the complex baseband signal, Re {} represents the real part of the complex baseband signal, and R (1) represents one lag autocorrelation. The method of claim 11, wherein the phase dispersion is
Figure 112016028333404-pat00029
(Mathematical formula)
Calculated by the above equation,
σ 2 represents the phase dispersion, R (0) represents zero lag autocorrelation, and R (1) represents one lag autocorrelation. The method of claim 11, wherein the upmixing unit,
A first upmixing cosine function multiplier configured to multiply a cosine function by the same phase component signal based on the smoothed phase shift to form a first upmixing signal;
A first upmixing sine function multiplier configured to multiply a sine function by the same phase component signal based on the smoothed phase shift to form a second upmixing signal;
A second upmixing cosine function multiplier configured to multiply a cosine function by the quadrature phase component signal based on the smoothed phase shift to form a third upmixing signal;
A second upmixing sine function multiplier configured to multiply a sine function by the quadrature phase component signal based on the smoothed phase shift to form a fourth upmixing signal;
A first adder coupled to the first upmix cosine function multiplier and the second upmix sine function multiplier, the first adder configured to add the first upmix signal and the fourth upmix signal;
A second adder coupled to the first upmixing sine function multiplier and the second upmixing cosine function multiplier and configured to add the second upmixing signal and the third upmixing signal
Ultrasound system comprising a. The method of claim 11, wherein the dynamic filtering unit,
Determine a bandwidth of the low pass filter based on the smoothed phase dispersion,
Determine a cutoff frequency of the low pass filter based on the bandwidth,
An ultrasonic system configured to form the low pass filter based on the bandwidth and the cutoff frequency. The method of claim 15, wherein the bandwidth,
Figure 112016028333404-pat00030
(Mathematical formula)
Calculated by the above equation,
B represents the bandwidth,
Figure 112016028333404-pat00031
Is an ultrasonic system representing the smoothed phase dispersion. The method of claim 15, wherein the cutoff frequency,
Figure 112016028333404-pat00032
(Mathematical formula)
Calculated by the above equation,
ω c, LPF represents the cutoff frequency, B represents the bandwidth,
Figure 112016028333404-pat00033
Is an ultrasonic system representing the smoothed phase dispersion. As a method of adaptively compensating for spectral downshift of a signal,
Transmitting, by an ultrasonic probe of an ultrasonic system, an ultrasonic signal to an object and receiving an ultrasonic echo signal from the object;
Forming, by the processor of the ultrasonic system, a complex baseband signal comprising an equal phase component signal and a quadrature phase component signal based on the ultrasonic echo signal;
Determining, by the processor, phase shift and phase dispersion based on the complex baseband signal;
Filtering, by the processor, the complex baseband signal by a dynamic filter to adaptively compensate for the spectral downshift of the ultrasonic echo signal based on the phase shift and the phase dispersion.
How to include. 19. The method of claim 18, wherein the dynamic filter comprises a band pass filter. 20. The method of claim 19, wherein determining the phase shift and the phase dispersion is:
Performing a Fourier transform on the complex baseband signal to form a Fourier transform signal;
Determining the phase shift and the phase dispersion based on the Fourier transform signal
How to include. 21. The method of claim 20, wherein the Fourier transform comprises a short-time Fourier transform (STFT). The method of claim 20, wherein the phase shift,
Figure 112016028333404-pat00034
(Mathematical formula)
Calculated by the above equation,
Δφ represents the phase shift, Im {} represents the imaginary part of the Fourier transform signal, Re {} represents the real part of the Fourier transform signal, and R (1) represents one-lag autocorrelation. How to indicate. The method of claim 20, wherein the phase dispersion is
Figure 112016028333404-pat00035
(Mathematical formula)
Calculated by the above equation,
σ 2 represents the phase dispersion, R (0) represents zero-lag autocorrelation, and R (1) represents one lag autocorrelation. The method of claim 20, wherein filtering the complex baseband signal comprises:
Performing a smoothing process on the phase shift and the phase dispersion;
Forming the band pass filter based on the smoothed phase shift and the phase dispersion;
Filtering the Fourier transform signal by the band pass filter;
Performing an inverse Fourier transform on the Fourier transform signal filtered by the band pass filter
How to include. The method of claim 24, wherein forming the band pass filter comprises:
Determining a bandwidth of the band pass filter based on the smoothed phase dispersion;
Determining a cutoff frequency of the band pass filter based on the bandwidth and the smoothed phase shift;
Forming the band pass filter based on the bandwidth and the cutoff frequency
How to include. The method of claim 25, wherein the bandwidth,
Figure 112016028333404-pat00036
(Mathematical formula)
Calculated by the above equation,
B represents the bandwidth,
Figure 112016028333404-pat00037
Represents the smoothed phase dispersion. The method of claim 25, wherein the cutoff frequency,
Figure 112016028333404-pat00038
(Mathematical formula)
Calculated by the above equation,
ω c represents the cutoff frequency, B represents the bandwidth,
Figure 112016028333404-pat00039
Represents the smoothed phase shift,
Figure 112016028333404-pat00040
Represents the smoothed phase dispersion. 19. The method of claim 18, wherein the dynamic filter comprises a linear time varying (LTV) low pass filter. The method of claim 28, wherein the phase shift,
Figure 112016028333404-pat00041
(Mathematical formula)
Calculated by the above equation,
Δφ represents the phase shift, Im {} represents the imaginary part of the complex baseband signal, Re {} represents the real part of the complex baseband signal, and R (1) represents one lag autocorrelation. The method of claim 28, wherein the phase dispersion is
Figure 112016028333404-pat00042
(Mathematical formula)
Calculated by the above equation,
σ 2 represents the phase dispersion, R (0) represents zero lag autocorrelation, and R (1) represents one lag autocorrelation. 29. The method of claim 28, wherein filtering the complex baseband signal comprises:
Performing a smoothing process on the phase shift and the phase dispersion;
Performing an upmixing process on the complex baseband signal based on the smoothed phase shift;
Forming the low pass filter based on the smoothed phase dispersion;
Filtering the upmixed complex baseband signal by the lowpass filter.
How to include. 32. The method of claim 31, wherein performing the upmixing process on the complex baseband signal comprises:
Multiplying a cosine function by the same phase component signal based on the smoothed phase shift to form a first upmix signal;
Multiplying a sine function by the same phase component signal based on the smoothed phase shift to form a second upmix signal;
Multiplying a cosine function by the quadrature phase component signal based on the smoothed phase shift to form a third upmix signal;
Multiplying a sinusoidal function by the quadrature phase component signal based on the smoothed phase shift to form a fourth upmix signal;
Adding the first upmix signal and the fourth upmix signal;
Adding the second upmix signal and the third upmix signal
How to include. 32. The method of claim 31, wherein forming the low pass filter comprises:
Determining a bandwidth of the low pass filter based on the smoothed phase dispersion;
Determining a cutoff frequency of the low pass filter based on the bandwidth;
Forming the low pass filter based on the bandwidth and the cutoff frequency
How to include. The method of claim 33, wherein the bandwidth,
Figure 112016028333404-pat00043
(Mathematical formula)
Calculated by the above equation,
B represents the bandwidth,
Figure 112016028333404-pat00044
Represents the smoothed phase dispersion. The method of claim 33, wherein the cutoff frequency is,
Figure 112016028333404-pat00045
(Mathematical formula)
Calculated by the above equation,
ω c, LPF represents the cutoff frequency, B represents the bandwidth,
Figure 112016028333404-pat00046
Represents the smoothed phase dispersion.
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