KR101646627B1 - Phase rotation beamformer and beamforming method for envelope error compensating - Google Patents

Abstract

The present invention relates to a phase rotation beam concentrator and a beam focusing method for amplitude error compensation, and more particularly, to a sampling unit for sampling a signal received by a transducer reflected from an image point into a digital signal. A mixer unit for separating the in-phase component and the quadrature component from the sampled digital signal; A sampling delay compensation unit for compensating a sampling delay for each of the in-phase component signal and the quadrature component signal from which the components are separated; A low pass filter unit for compensating an amplitude error of the in-phase component signal and the quadrature component signal whose sampling delay is compensated; A decimation unit for reducing the amount of data whose signal band is lowered to a baseband; And a phase rotation unit for performing phase rotation on the decimated signal; And a control unit.
With this configuration, the phase rotation beam concentrator and the beam focusing method for amplitude error compensation of the present invention have an advantage that the amount of data can be reduced by the baseband signal processing in the existing phase rotation beam concentrator and beam focusing method, It is possible to accurately and efficiently perform the beam focusing by compensating the beam focusing amplitude error generated according to the transmission signal.

Description

[0001] The present invention relates to a phase rotation beamformer and a beamforming method for compensating for amplitude errors,

The present invention relates to a phase rotation beam concentrator and a beam focusing method for amplitude error compensation. More particularly, the present invention relates to a phase rotation beam concentrator and a beam focusing method for efficiently compensating an amplitude error generated in a received signal by transmitting a broadband signal, And more particularly to a phase rotating beam concentrator and a beam focusing method for compensating a phase rotation beam.

As IT technology develops rapidly, IT technology is converging in other fields. In particular, IT technology is being widely applied to medical field. The medical ultrasonic wave, which is one of the technologies that IT technology is applied to the medical field, uses ultrasound signals to visualize the size, structure and pathological damage of muscles, tendons, internal organs and internal organs in the human body as tomographic images in real time It is one of diagnostic medical imaging technology.

Such medical ultrasound technology can measure the energy of an ultrasound signal reflected from the inside of the human body to non-invasively image the inside of the human body. At this time, the ultrasound dynamic receive beam focusing is a technique of focusing and restoring an ultrasound signal reflected at each depth in the human body and returning to a transducer. The ultrasound dynamic receive beam focusing is a technique of adjusting the lateral direction resolution of the ultrasound image and the axial direction ) It is mainly used to increase the resolution.

FIG. 1 is a conceptual diagram of a transmitting / receiving beam focusing according to the prior art. FIG. 1 (a) shows a transmitting beam focusing process and FIG. 1 (b) shows a receiving beam focusing process.

As shown in Fig. 1 (a), the transmission beam focusing is performed by applying a variable delay time in each array transducer of the transducer during beam transmission so as to converge to one focusing point, and the inphase component (Beam focusing) such that the constructive interference occurs, and the remaining components except the in-phase component of the signal are canceled by destructive interference.

1 (b), the ultrasonic signals reflected from the object are input to the array elements of the transducer. At this time, since the distances from the object to the array elements are different from each other, the time at which the ultrasonic signals reflected from the object are received by the array element also differs. Accordingly, after applying a different delay time to the plurality of ultrasonic signals according to the distance between the object and each array element, the plurality of ultrasonic signals are converged and restored.

Particularly, when the interval of the signal data constituting the sampled image is delayed more than 16 times the center frequency of the ultrasonic array transducer in terms of delay resolution, precise beam focusing is possible. However, when the system is implemented using the high-speed sampling, it is inefficient considering the cost. Therefore, the signal is typically sampled at 4 to 8 times the center frequency, and the remaining 2 to 4 times the finer resolution depends on the type of the beam concentrator Apply them in different ways. The types of beam focusing are different according to the method of implementing the fine delay resolution. The types of beam focusing devices include an interpolation beam concentrator, a fractional delay filter beam concentrator, a phase rotator, Beam concentrators, and analytic signal beam concentrators.

In this case, the interval or delay resolution of the sampled signals is referred to as a coarse delay (rough delay), and the delay resolution interval applied using the beam concentrator is referred to as a fine delay.

 Among them, the phase rotation beam concentrator applies a fine delay of 16 times or more the center frequency through the phase rotation of the signal based on the center frequency of the transmission signal. At this time, the received signal is demodulated And moves to a baseband which is a frequency band. Therefore, the signal after the demodulation process can be decimated to reduce the amount of data.

However, in the phase rotation method, only the delay time compensation for the phase of the amplitude and the phase of the signal is possible, so that an envelope error occurs. Such an envelope error occurs largely as the bandwidth of the transmission signal becomes wider, Resulting in reduced beam focusing accuracy.

KR 10-2013-0090219 Pixel-based focusing system using phase rotation technique, Sogang University Industry-Academic Cooperation Foundation, Aug. 13, 2013.

In order to solve the problems of the conventional art as described above, the present invention performs not only the delay time compensation for phase but also the delay time compensation for the envelope error without increasing the data amount, thereby achieving more accurate and efficient beam focusing And to provide a phase rotation beam concentrator structure and a beam focusing method to be performed.

A phase rotation beam concentrator for amplitude error compensation used in an ultrasound imaging system for solving the above problems includes a sampling unit for sampling a signal received by a transducer reflected from an image point into a digital signal; A mixer unit for separating the in-phase component and the quadrature component from the sampled digital signal; A sampling delay compensator for compensating a sampling delay in units of a sampling period for each of the in-phase component signal and the quadrature component signal from which the components are separated; A low pass filter unit for compensating an amplitude error of the in-phase component signal and the quadrature component signal whose sampling delay is compensated; A decimation unit for reducing the amount of data whose signal band is lowered to a baseband; And a phase rotation unit for performing phase rotation on the decimated signal; And a control unit.

More preferably, the in-phase component signal subjected to the sampling delay and the quadrature component signal are subjected to zero padding and interpolated through a low-pass filter, based on a fine delay calculated by the delay time calculator And a low pass filter for selecting and outputting specific data.

Particularly, it may include a low-pass filter unit composed of a polyphase interpolation filter.

More preferably, in a multi-phase filter structure based on a low-pass filter including a filtering range of an orthogonal demodulation LPF and an interpolation low-pass filter, a plurality of subset filters of the same order are arranged in parallel And a low-pass filter having a data throughput of the plurality of subset filters equal to or lower than a sampling frequency.

More preferably, a fine delay at a specific image point is checked for the output signals of the plurality of subset filters, and an output signal of one subset filter among the output signals of the plurality of subset filters is selected based on the determined fine delay A multiplexer for outputting; And a low-pass filter unit that further includes a low-pass filter unit.

And a multiplexer unit for selecting one of the predetermined filter coefficient sets for the plurality of subset filters according to the fine delay time at the specific image point and outputting the output signal of the subset filter having the selected filter coefficient .

In order to solve the above problems, a method of focusing a phase rotation beam for amplitude error compensation used in an ultrasound imaging system includes sampling a signal received by a sampling unit as a digital signal by being reflected from an image point; Separating the in-phase component and the quadrature component from the sampled digital signal; Compensating a sampling delay for each of the in-phase component signal and the quadrature component signal from which the sampling delay compensation sub-component is separated; Compensating the amplitude error for the in-phase component signal and the quadrature component signal with the low-pass filter added sampling delay compensation; Reducing the amount of data whose decimation-added signal band is lowered to a baseband; And performing a phase rotation on the decimated signal.

More preferably, the in-phase component signal subjected to the sampling delay and the quadrature component signal are subjected to zero padding and interpolated through a low-pass filter, based on a fine delay calculated by the delay time calculator And compensating the amplitude error for the in-phase component signal and the quadrature component signal by the low-pass filter unit for selecting and outputting the specific data.

More preferably, in a multi-phase filter structure based on a low-pass filter including a filtering range of an orthogonal demodulation LPF and an interpolation low-pass filter, a plurality of sub- And the data throughput is the same or lower than the sampling frequency. The low-pass filter may compensate for the amplitude error for the in-phase component signal and the quadrature component signal.

The sub-filter may further include a sub-band filter for checking the fine delay at a specific image point with respect to the output signals of the plurality of subset filters, selecting one output signal among the output signals of the plurality of subset filters based on the determined fine delay, And compensating the amplitude error for the in-phase component signal and the quadrature component signal by the pass filter section.

In particular, a low pass filter that selects one of the filter coefficients of a predetermined set of filter coefficients for the plurality of subset filters according to the fine delay time at the specific image point, and outputs an output signal of the subset filter having the selected filter coefficient And compensating the amplitude error for the additional in-phase component signal and the quadrature component signal.

The phase rotation beam concentrator and beam focusing method for amplitude error compensation of the present invention compensates an amplitude error caused by a broadband transmission signal through an application multi-phase filter, Accuracy can be expected to be improved. Thus, it is possible to reduce the amount of data through the baseband signal processing of the general phase rotation beam concentrator and to improve the accurate beam focusing performance at the same time.

In addition, the present invention can be advantageously applied to a situation in which data acquired by an ultrasonic probe system configured wirelessly in an environment having limited communication throughput needs to be transmitted to a system located at a distance from the system. Therefore, the phase rotation beam focusing and focusing method can be effectively used in point-of-care (POC) ultrasonic waves and wireless ultrasonic waves.

1 is a conceptual diagram of a general transmit / receive beam focusing.
2 is a diagram illustrating a phase rotation beam concentrator for amplitude error compensation according to an embodiment of the present invention.
3 is a diagram illustrating the phase rotation in the complex plane.
4 is a diagram illustrating a phase rotation beam concentrator implementation process for amplitude error compensation.
5 is a graph illustrating a frequency response of a low-pass filter used in FIG. 4 according to an embodiment of the present invention.
6 is a diagram illustrating a general filtering process of a combined low-pass filter.
FIG. 7A is a diagram illustrating a low-pass filter structure in FIG. 6 in a multiphase filter structure.
7B is a view illustrating a low-pass filter unit composed of one subset filter and a plurality of subset filter coefficient sets, instead of the multi-phase filter structure.
FIG. 8 is a diagram illustrating a transmission / reception distance model of an ultrasonic signal for applying the equation of the present invention.
FIG. 9 is a beam focusing output image output according to the present invention and prior art, respectively.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Hereinafter, the present invention will be described in detail with reference to preferred embodiments and accompanying drawings, which will be easily understood by those skilled in the art. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

First, before describing the present invention, an ultrasonic beam focusing process used in an image system using an ultrasonic signal will be briefly described.

Ultrasonic beam focusing methods are classified into transmission beam focusing and receiving beam focusing.

The transmit beam focusing refers to a method of causing the beam to converge at one focus point in the beam transmission, reflecting the variable time in each array element for the transducer.

In the receiving beam focusing method, an ultrasonic signal reflected from an image point arrives at each of the array elements at different times. After applying a time delay to the array elements for each of the ultrasonic signals, When the ultrasonic signals are added together, the phases of the ultrasonic signals reflected from the object and received as the transducers coincide with each other, thereby having the largest amplitude.

In order to acquire a high-resolution ultrasound image through such a beam focusing method, the variable time delay value allocated to each array transformer should be sampled at 16 times the array transformer center frequency fo, but the A / D sampling converter Converter and a memory size used for focusing are firstly sampled at a sampling frequency of about 4 to 8 times lower than the center frequency and then interpolated by a factor of 2 to 4 , 16f ₀ , which is about 16 times the center frequency, and used in a digital beam focusing system.

Of the various methods used for beam focusing, the phase rotation beam focusing method obtains a fine delay resolution for the phase through the phase rotation of the signal with respect to the center frequency. At this time, the signal moves to a baseband which is a low frequency band through a demodulation process. Therefore, the signal output from the phase rotation beam focusing unit can be decimated within a range where an aliasing error does not occur, thereby lowering the data processing rate.

Hereinafter, a phase rotation beam concentrator for amplitude error compensation according to an embodiment of the present invention will be described in detail with reference to FIG.

2 is a diagram illustrating a phase rotation beam concentrator for amplitude error compensation according to an embodiment of the present invention.

2, the phase rotation beam concentrator 100 for amplitude error compensation of the present invention includes a sampling unit 110, a mixer unit 120, a sampling delay compensation unit 130, a low-pass filter unit 140, a decimation unit 150, and a phase rotation unit 160.

The sampling unit 110 receives the signal reflected from the image point and samples it as a digital signal.

The mixer unit 120 samples the inphase component signal and the quadrature component signal from the digital signal through an orthogonal demodulation process of performing COS and SIN multiplication on the sampled digital signal with reference to the center frequency Respectively, so that the signal band can be lowered to the baseband.

The sampling delay compensation unit 130 compensates the sampling delay time of the sampling interval for the in-phase component signal and the quadrature component signal, respectively. That is, the sampling delay compensator 130 receives the sampling delay time and the fine delay time from the delay calculator together with the low-pass filter 140, and performs filtering for fine delay compensation on the data with the sampling delay compensated It is possible to control the sampling delay to compensate the input data in units of registers in the low pass filter unit 140. [

The low pass filter 140 compensates the fine delay time for the envelope that can not be compensated for by phase rotation after zero padding for the in-phase component signal and the quadrature component signal for which the sampling delay time is compensated .

Particularly, the low-pass filter of the low-pass filter unit 140 includes a quadrature demodulation LPF used for a conventional ultrasound image processing and an interpolation LPF used to compensate for amplitude Filtering range, and may be implemented with, for example, a polyphase interpolation filter.

The low-pass filter of the low-pass filter unit 140 further includes a multiplexer that is connected to a plurality of subset filters H ₀ -H _{L -1 in} parallel with each other and to a rear end of a plurality of subset filters connected in parallel to each other . The multiplexer selects and outputs one of the output signals of the plurality of subset filters (H ₀ - H _{L -1} ) to which the fine delay calculated by the delay calculator is applied. The order of each of the plurality of subset filters having such a multi-phase structure may be one of a quadrature demodulation LPF and an interpolation LPF used for compensating the amplitude. (N / L) obtained by dividing the low-pass filter degree (N) by the interpolation ratio (L).

Finally, a plurality of subset filter structures connected in parallel in the low-pass filter unit 140 may be configured to include both a low-pass filter having the order of the subset filter and a filter coefficient set for the subset filter . At this time, one subset filter coefficient is selected from the subset filter coefficient sets according to the fine delay of the corresponding image point with reference to the delay calculator through the filter coefficient of the low-pass filter, Thereby compensating for the fine delay.

The decimation unit 150 performs an operation of subtracting data from the output signal of the low-pass filter unit 140 down to the baseband so that the amount of the output signal is reduced to a specific ratio within a range where there is no aliasing error do.

The phase rotation unit 160 performs phase rotation on the signal to compensate the sampling delay time and the fine delay time for the phase of the signal.

FIG. 3 is a diagram illustrating a phase rotation in a complex plane, which can be expressed by the following equation (1).

(I) and quadrature component (Q) are multiplied by the COS and SIN values corresponding to the phase to be compensated to output the in-phase component data and quadrature component data in which the desired phase is compensated, respectively, as shown in Fig. 3 and Lt; / RTI >

Hereinafter, the structure of the phase rotation beam concentrator for amplitude error compensation will be described in detail with reference to FIG.

FIG. 4 is a block diagram illustrating a structure of a phase rotation beam concentrator for amplitude error compensation according to the present invention. FIG. 4 is a block diagram of a beam focusing system for compensating an amplitude error through interpolation after orthogonal demodulation of a signal. 4 (a). 4 (a) can be represented by the structure shown in FIG. 4 (b) based on the Multirate signal processing theory. In particular, the structure including two filters, that is, an orthogonal demodulation low pass filter and an interpolation low pass filter Can be represented as shown in FIG. 4 (c). Finally, as shown in FIG. 4 (e), the structure can compensate for the amplitude error through the low-pass filter.

FIG. 5 is a graph showing the frequency response of the pass filter shown in FIG. 4. FIG. 5 (a) shows the frequency response of the quadrature demodulation low-pass filter H ₁ (z) 5 (c) shows the frequency response of the filter H ₂ (z). FIG. 5 (c) shows the frequency response of the low-pass filter H Lt; RTI ID = 0.0 > low-pass < / RTI >

Thus, the frequency response of the low-pass filter including both the range of the orthogonal demodulation low-pass filter and the range of the interpolation low-pass filter is multiplied by the frequency response of the orthogonal demodulation low-pass filter and the frequency response of the interpolation low- .

Accordingly, the frequency response of the low-pass filter H (z), which is the sum of the range of the orthogonal demodulation low-pass filter and the range of the interpolation low-pass filter, is as shown in Fig. 5 (c). Therefore, the filter coefficient of the low-pass filter H (z) including both the ranges of the two filters can be obtained by designing based on the obtained pass band frequency and the stop band frequency.

Hereinafter, the multi-phase filter structure according to the prior art and the present invention will be described with reference to FIGS. 6 to 7. FIG.

For the sake of clarity, the filter assumes, for example, that the sampled data intervals sampled at four times the center frequency are implemented at 16 times the center frequency using a beam concentrator.

FIG. 6 is a diagram illustrating a general interpolation filtering process. After performing zero padding on the sampled data according to a desired interpolation coefficient, interpolation low-pass filtering is performed to output all data having a 16f ₀ delay resolution. However, this involves unnecessary computational processes such as multiplying the zero padded data by the filter coefficients.

FIG. 7 is a diagram illustrating a multiphase structure filtering process according to an exemplary embodiment of the present invention. Referring to FIG.

As shown in FIG. 7A, may be implemented by a multi-phase filter structure based on a low-pass filter including a filtering range of an quadrature demodulation LPF and an interpolation low-pass filter (LPF) . As described above, when the low-pass filter is implemented as an application multi-phase filter structure, it can be realized by using a subset filter having no useless operation process in the conventional filter. In this case, each subset filter structure is the same, .

In other words, since the conventional interpolation low-pass filter process is implemented with a multi-phase filter structure, it is unnecessary to perform unnecessary calculation, so that the calculation can be simplified and the processing speed can be improved.

In addition, a plurality of subset filters (H ₀ to H _{L -1} ) in the above-described filter structure are connected in parallel with each other and connected to a multiplexer disposed at the subsequent stage.

The multiplexer selects a subset filter for outputting a signal to which the fine delay calculated by the delay time calculator is applied among the data applied up to the fine delay resolution of 16f ₀ , which is the output of the plurality of subset filters (H ₀ to H _{L -1} ) And outputs the signal output from the selected subset filter as a final output signal.

At this time, the throughputs of the plurality of subset filters of the low-pass filter unit may be maintained at the same or lower than the sampling frequency of the signal sampled from the signal received by the transducer after being reflected from the initial image point. That is, the phase rotation beam concentrator or the beam focusing method including the low-pass filter unit of the present invention can compensate for the amplitude error in the phase rotation beam focusing through the multiphase interpolation filter while maintaining the data throughput of the input- have.

Finally, as shown in FIG. 7B, each subset filter existing in the multi-phase filter structure is replaced with one low-pass filter, and the fine delay of the corresponding image point is checked. Based on the fine delay, It is possible to perform filtering in such a manner that only the update is performed. Accordingly, it is possible to output only the data corresponding to the desired fine delay, so that the data processing rate does not increase, and the number of subset filters existing by the interpolation ratio L is reduced to one, thereby drastically reducing the hardware cost .

Hereinafter, the envelope error is confirmed through an equation, and a method for compensating for the amplitude error is also confirmed by the following equation.

8 is a diagram showing a transmission / reception distance model of an ultrasonic signal.

은 초음파 변환자 배열소자(element)부터 깊이 방향으로 k번째 영상점까지의 거리를 나타내고,

는 k번째 영상점에서 반사되어 i번째 배열소자로 수신 시 초음파 신호의 직선 거리를 나타낸다. As shown in Fig. 8,

Represents the distance from the ultrasound transducer array element to the k-th image point in the depth direction,

Represents the straight line distance of the ultrasonic signal when it is reflected to the i-th array element at the k-th image point.

First, the ultrasonic transmission signal can be defined by the following equation (2).

만큼의 시간이 지연되어 수신됨에 따라, 수신 신호

는 하기의 수학식 3과 같이 정의할 수 있다. At this time, a signal is transmitted from a center element, and a signal received by an i-th element is used as a reference. At this time, after the central array element transmits a signal,

Lt; RTI ID = 0.0 > received signal < / RTI >

Can be defined as Equation (3) below.

는 초음파 신호를 중심 배열소자(center element)에서 송신 후, k번째 영상점으로부터 반사되어 i 번째 배열소자(center element)에 수신 되기까지 소요된 총 시간을 나타내며, 상기 총 시간은 하기의 수학식 4와 같이 나타낼 수 있다. At this time,

Represents the total time taken for the ultrasonic signal to be transmitted from the center element to be reflected from the kth image point and received by the i-th array element, and the total time is expressed by the following equation As shown in Fig.

Here, c represents the traveling speed (average 1540 m / s) of the ultrasonic signal transmitted into the tissue of the human body.

및

는 하기의 수학식 5와 같이 나타낼 수 있다.Further,

And

Can be expressed by the following equation (5).

는 표본화 간격

을 나타내며, 상기

는

에서

를 차감한 거리를 나타내고, 상기

는 신호의 표본화 간격에 해당하는 잔여 거리

와 미세 지연 시간 간격에 해당하는 잔여 거리

간의 합으로 하기의 수학식 6과 같이 나타낼 수 있다. At this time,

Sampling interval

, And

The

in

Represents a distance obtained by subtracting

Is the residual distance corresponding to the signal sampling interval

And the residual distance corresponding to the fine delay time interval

Can be expressed by the following equation (6).

는 하기의 수학식 7과 같다. At this time, the total delay time

Is expressed by Equation (7) below.

Accordingly, the received signal that is sampled and reflects the total delay time can be expressed by Equation (8).

Herein, n is a time index of the sampled signal.

와 직교 성분(Quadratue) 데이터

로 분리하면, 하기의 수학식 9와 같이 나타낼 수 있다. The quadrature demodulation process is performed by multiplying the received signal by cos and -sin and passing through a low pass filter to obtain inphase data

And quadrature data

The following equation (9) can be obtained.

The in-phase component data and the quadrature component data are expressed by an analytic signal as shown in Equation (10).

The coarse delay, which is a delay resolution, can be compensated for in such data, as shown in Equation (11).

Next, a phase value to be compensated for the signal through the phase rotation unit is expressed by Equation (12).

: 전체 배열소자로 입력된 같은 깊이의 영삼점에 해당하는 수신신호의 보상해주어야 하는 위상은 동일하므로, 따로 보상해주지 않아도 된다.)(

: It is not necessary to compensate the received signal corresponding to the same depth of the input signal input to the entire array element, since the phase to be compensated is the same.)

Next, the above phase value is compensated for as shown in Equation (13).

Therefore, the signal of one image point obtained by beam-combining the received signals of all array elements is expressed by Equation (14).

Here, N represents the total number of channels of the system.

Accordingly, the cumulative error E of all the channels is expressed by Equation (15) below.

Hereinafter, the process of compensating the amplitude error through the phase rotation beam focusing and beam focusing method for amplitude error compensation according to the present invention will be described in detail with reference to the mathematical expression.

Generally, the method of selecting data according to the fine delay time calculated by the post-interpolation delay time calculation unit and the method of selectively using the output of the multiphase filter output the same result. Therefore, based on the interpolation filter- .

은 응용 다중 필터를 거치면서,

배 만큼 보간된 표본화 간격이 수학식 16과 같이 변경된다.The sampling interval

Through the application multi-filter,

The sampling interval interpolated by the number of times is changed as shown in equation (16).

The total delay time of Equation (16) to which the changed sampling interval is applied can be changed as shown in Equation (17) below.

는 미세 지연 시간 간격의 잔여 시간을 나타내기 때문에

간격으로 나타낼 수 있으며, 이를 통해 총 지연시간

는 아래 수학식 18과 같이 나타낼 수 있다.Here,

Quot; represents the remaining time of the fine delay time interval

It can be expressed as an interval,

Can be expressed by the following equation (18).

는 앞서 변경된 표본화 간격에 따라 바뀐 깊이 방향의 지연시간을 나타내고, 상기

는 각 채널마다의 변경된 표본화 간격이 적용된 잔여시간을 나타낸다. At this time,

Represents the delay time in the depth direction changed according to the sampling interval changed before,

Represents the remaining time to which the changed sampling interval for each channel is applied.

Therefore, the analytic signal to which the residual time is applied can be expressed by Equation (19).

이 보상된 신호는 하기의 수학식 20과 같다.Depending on the sampling interval changed here, the time delay

This compensated signal is shown in Equation 20 below.

The final output obtained by compensating the phase-compensated signal through the phase rotator for the time-delay-compensated signal is given by Equation (21).

That is, if the cumulative envelope error of all channels generated in the conventional phase rotation beam scanner or beam focusing method is equal to Equation (15), the phase rotation beam scanner or beam focusing method for amplitude error compensation according to the present invention The cumulative amplitude error is 0 as shown in Equation (22).

Hereinafter, referring to FIG. 9, the beam focusing output images output from the prior art and the present invention will be compared with each other.

9 shows a Point-spread-function image of a Wire-Point-target using a field 2 simulation.

9 (a) shows an output image through an interpolation beam concentrator or a beam focusing method which is widely used in a conventional beam concentrator, and FIG. 9 (b) shows an output image through a conventional phase rotating beam concentrator Or an output image through a beam focusing method. FIG. 9C shows an output image through a phase rotation beam concentrator or a beam focusing method including amplitude error compensation through the present invention.

9 (b) and 9 (c), when using the prior art phase rotation beam concentrator or the beam focusing method shown in FIG. 9 (b), a noticeable image difference 9 (a) and 9 (c) are compared with each other at the same position, it is confirmed that the image restoration performance is equivalent. Accordingly, it can be seen that the amplitude error is compensated through the present invention to provide more accurate beam focusing performance as compared with a general phase rotation beam concentrator or a beam focusing method.

In addition, the phase rotation beam focusing method for amplitude error compensation can be stored in a computer-readable recording medium on which a program for executing by a computer is recorded. At this time, the computer-readable recording medium includes all kinds of recording apparatuses in which data that can be read by a computer system is stored. Examples of the computer readable recording medium include ROM, RAM, CD-ROM, DVD 占 ROM, DVD-RAM, magnetic tape, floppy disk, hard disk, optical data storage, and the like. In addition, the computer-readable recording medium may be distributed to network-connected computer devices so that computer-readable codes can be stored and executed in a distributed manner.

The phase rotation beam concentrator and beam focusing method for amplitude error compensation of the present invention uses a low-pass filter in a low-pass filter unit and a filter coefficient set and a multiplexer of a subset filter in a polyphase filter structure to generate data It is possible to improve the accuracy of the beam focusing efficiently by performing the decimation of the processed baseband signal while compensating for the amplitude error without increasing the throughput.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Do.

110: Sampling unit (ADC) 120: Mixer unit
130: Sampling delay compensation unit 140: Low pass filter unit
150: decimation unit 160: phase rotation unit

Claims (12)

A phase-shifting beam concentrator for amplitude error compensation used in an ultrasound imaging system,
A sampling unit for sampling the signal reflected from the image point and received by the converter into a digital signal;
A mixer unit for separating the in-phase component and the quadrature component from the sampled digital signal;
A sampling delay compensator for compensating a sampling delay in units of a sampling period for each of the in-phase component signal and the quadrature component signal from which the components are separated;
A low pass filter unit for compensating an amplitude error of the in-phase component signal and the quadrature component signal whose sampling delay is compensated;
A decimation unit for reducing the amount of data whose signal band is lowered to a baseband; And
A phase rotation unit for performing phase rotation on the decimated signal;
, ≪ / RTI &
The low-pass filter unit
A quadrature demodulation LPF, and an interpolation LPF. The output signal of the subset filter includes a fine delay to an envelope of the output signal of the subset filter. And outputting the amplified amplitude error signal.
The method according to claim 1,
The low-pass filter unit
The interpolated data of the in-phase component signal to which the sampling delay is applied and the quadrature component signal after zero padding after the interpolation by low-pass filtering, the specific data based on the fine delay calculated by the delay time calculator And outputting the amplified amplitude error signal.
The method according to claim 1,
The low-pass filter unit
And a polyphase interpolation filter configured based on a low-pass filter including a filtering range of the orthogonal demodulation low-pass filter and the interpolation low-pass filter.
The method of claim 3,
The low-pass filter unit
Wherein a plurality of subset filters of the same order are connected in parallel in the multi-phase filter structure, and a data processing rate of the plurality of subset filters is equal to or lower than a sampling frequency.
5. The method of claim 4,
The low-pass filter unit
A multiplexer for checking the fine delay at a specific image point with respect to the output signals of the plurality of subset filters and selecting and outputting the output signal of one subset filter among the output signals of the plurality of subset filters based on the confirmed fine delay;
Further comprising a phase detector for detecting the amplitude error of the phase rotation beam.
6. The method of claim 5,
The multiplexer
Selecting one filter coefficient among the filter coefficients set for the plurality of subset filters according to a fine delay time at a specific image point and outputting an output signal of the subset filter having the selected filter coefficient, Phase rotating beam concentrator for compensation.
A phase rotation beam focusing method for amplitude error compensation used in an ultrasound imaging system,
Sampling the signal received by the sampling unit as a digital signal by being reflected from the image point;
Separating the in-phase component and the quadrature component from the sampled digital signal;
Compensating a sampling delay of sampling period unit for each of the in-phase component signal and the quadrature component signal from which the sampling delay compensating sub-component is separated;
Compensating the amplitude error for the in-phase component signal and the quadrature component signal with the low-pass filter added sampling delay compensation;
Reducing the amount of data whose decimation-added signal band is lowered to a baseband; And
Performing a phase rotation on the decimated signal;
, ≪ / RTI &
The step of compensating the amplitude error for the in-phase component signal and quadrature component signal of the low-
A quadrature demodulation LPF, and an interpolation LPF. The output signal of the subset filter includes a fine delay to an envelope of the output signal of the subset filter. And outputting the phase rotation beam focusing signal.
8. The method of claim 7,
The step of compensating the amplitude error for the in-phase component signal and quadrature component signal of the low-
The interpolated data of the in-phase component signal to which the sampling delay is applied and the quadrature component signal after zero padding and interpolated through the low-pass filter, based on the fine delay calculated by the delay time calculator, And outputting the phase rotation beam focusing signal.
8. The method of claim 7,
The step of compensating the amplitude error for the in-phase component signal and quadrature component signal of the low-
Wherein a data processing rate of each subset filter connected in parallel in a multi-phase filter structure based on a low-pass filter including a filtering range of the orthogonal demodulation low-pass filter and the interpolation low-pass filter is equal to or lower than a sampling frequency Wherein the phase rotation beam focusing method comprises the steps of:
10. The method of claim 9,
The step of compensating the amplitude error for the in-phase component signal and quadrature component signal of the low-
Characterized by confirming a fine delay at a specific image point with respect to the output signals of the plurality of subset filters and selecting and outputting one of the output signals of the plurality of subset filters based on the determined fine delay. A method of focusing a phase rotation beam for error compensation.
11. The method of claim 10,
The step of compensating the amplitude error for the in-phase component signal and quadrature component signal of the low-
Wherein one of the plurality of subset filters is selected in accordance with the fine delay time at the specific image point and the output signal of the subset filter having the selected filter coefficient is outputted. A method of focusing a phase rotation beam for error compensation.
A computer-readable recording medium on which a program for executing a method according to any one of claims 7 to 11 is recorded.

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