Intensity-controllable ultrasonic envelope segmented extraction method

Abstract

The invention discloses an intensity-controllable ultrasonic envelope segmentation extraction method. The method comprises the following steps that 1, ultrasonic equipment obtains an A scanning signal # imgabs0 # from a probe; step 2, adopting Hilbert transform to obtain an envelope signal # imgabs2 # of the A scanning signal # imgabs1 #; step 3, aligning the A scanning signal # imgabs3 # and the envelope signal # imgabs4 #, and taking an absolute value to obtain a signal # imgabs5 #; 4, setting the envelope weight # imgabs6 #, the envelope weight # imgabs7 # and the envelope weight # imgabs8 # to be integers which are greater than or equal to 1; performing segmentation setting on the envelope weight # imgabs9 # according to an ultrasonic scanning time axis so as to control envelope signals of different segments; the envelope signal # imgabs10 # and the signal # imgabs11 # are multiplied by the envelope weight # imgabs12 # and the envelope weight # imgabs13 # respectively and then added, the envelope weight # imgabs12 # and the envelope weight # imgabs13 # are shifted rightwards by the bit # imgabs14 #, and the envelope signal after ultrasonic segmented weighting is obtained. According to the intensity-controllable ultrasonic envelope segmented extraction method disclosed by the invention, the defect that different intensities cannot be adopted in different segments during existing ultrasonic envelope extraction is overcome.

Description

Technical Field

[0001] The present invention belongs to the technical field of ultrasonic non-destructive testing, and specifically relates to a method for segmentally extracting ultrasonic envelopes with controllable intensity. Background Art

[0002] In the field of industrial ultrasonic testing, in order to better view and analyze defects, video filtering is often turned on to extract the envelope of the ultrasonic A-scan, so that the defect signal becomes more rounded and closer to the actual situation. Currently, the Hilbert transform method is mostly used to extract the envelope of ultrasonic signals. After this method is turned on, it will extract the envelope of the entire ultrasonic A-scan signal, but this method cannot adjust the intensity of the extracted envelope, which will cause inconvenience in use. When the distance between the defect signal and the interface is very close, such as defects near the surface, near the bottom surface, and near the joint of two materials, when the video filtering is turned on and the envelope is extracted, the defect signal may be fused with the interface wave signal, resulting in the defect signal being unable to be observed. After this situation occurs, although the method of not turning on the video filtering can be used to view these defect signals, if there are also defects in other positions of the workpiece being detected that are not close to the interface at this time, the defect signals in other positions will have a poor visual effect due to the lack of video filtering. In particular, during the process of automated scanning, it is often required that the ultrasonic scanning image be more perfect, and it is hoped that the defect signals at the interface position and the defect signals at other positions can be observed simultaneously. Then, the video filtering intensity at the interface position and the video filtering intensity at other positions need to be different. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a method for segmentally extracting ultrasonic envelopes with controllable intensity, which solves the deficiency that different intensities cannot be used in different segments during the extraction of existing ultrasonic envelopes.

[0004] To achieve the above purpose, the present invention provides the following technical solutions: A method for segmentally extracting ultrasonic envelopes with controllable intensity, comprising the following steps: Step 1: The ultrasonic device obtains the A-scan signal from the probe ; Step 2: Use the Hilbert transform to obtain the envelope signal of the A-scan signal ; ; Step 3: Align the A-scan signal with the envelope signal , and then take the absolute value to obtain the signal ; Step 4: Set the envelope weight , , as an integer greater than or equal to 1; According to the ultrasonic scanning time axis, for the envelope weight Perform segmented setting to control the envelope signals of different segments; Multiply the envelope signal and the signal respectively with the envelope weight and , then add them together, and shift right by bits to obtain the envelope signal after ultrasonic segmented weighting.

[0005] Furthermore, in the second step, the envelope signal is: Where: is the imaginary part of the Hilbert transform analytic signal; is the real part of the Hilbert analytic signal.

[0006] Furthermore, the imaginary part of the Hilbert transform analytic signal is output by an FIR filter. The FIR filter is designed as an all-pass filter with a passband gain of 1, a phase characteristic of -90° phase shift for positive frequencies and 90° phase shift for negative frequencies, and the order is designed as an even order.

[0007] Furthermore, the real part of the Hilbert analytic signal is obtained by performing phase compensation on the A-scan signal . The phase compensation is achieved through time delay. The time delay is each clock cycle, and: Where: is the order of the FIR filter design; is the fixed delay generated by the register logic during the FIR filter design.

[0008] The beneficial effects of the present invention are as follows: The method for extracting the intensity-controllable ultrasonic envelope segments of the present invention, by obtaining the envelope signal of the A-scan signal through the Hilbert transform, then aligning the A-scan signal with the envelope signal through time delay and taking the absolute value to obtain the signal ; In this way, the envelope signal and the signal can be subjected to segmented weight superposition, and the envelope weight of the envelope signal is set to , and the envelope weight of the signal is set to . In this way, the signal obtained after superposition is shifted right by By shifting the phase of the ultrasonic signal by 90 degrees, an envelope signal weighted by ultrasonic waves is obtained, which solves the problem that different intensities cannot be used in different segments during the extraction of the existing ultrasonic envelope, and has the following advantages: (1) The video filtering intensity of ultrasonic detection is adjustable, and A-scan signal envelopes with different intensities can be obtained; (2) The envelope weights are segmented according to the ultrasonic scanning time axis to control the envelope signals of different segments. In this way, different intensities of envelopes can be set for different segments of the same A-scan signal, more satisfactory envelope signals can be obtained, and the requirements for simultaneously observing defect signals at the interface position and defect signals at other positions can be met. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to make the objectives, technical solutions, and beneficial effects of the present invention clearer, the following drawings are provided for description of the present invention: Figure 1 It is a flowchart of an embodiment of the method for extracting ultrasonic envelope segments with controllable intensity according to the present invention; Figure 2 It is a schematic diagram of obtaining an envelope signal through an FPGA ; Figure 3 It is a schematic diagram of a segmented weight superposition module; Figure 4 It is a schematic diagram of setting the envelope intensity to three segments; Figure 5 It is the envelope signal after ultrasonic segmentation weighting obtained. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0010] The present invention will be further described below in conjunction with the drawings and specific embodiments, so that those skilled in the art can better understand the present invention and implement it, but the embodiments given are not intended to limit the present invention.

[0011] As shown in Figure 1 , the method for extracting ultrasonic envelope segments with controllable intensity in this embodiment includes the following steps.

[0012] Step 1: The ultrasonic device obtains an A-scan signal from the probe .

[0013] Step 2: Use the Hilbert transform to obtain the envelope signal of the A-scan signal ; .

[0014] Specifically, the time-domain conversion formula of the Hilbert transform is: Where: represents the Hilbert transform.

[0015] In terms of the spectrum, the Hilbert transform multiplies the positive frequency part of the original signal by -j and the negative frequency part by j. That is, under the condition of keeping the amplitude unchanged, the positive frequency is phase-shifted by -90°, and the negative frequency component is phase-shifted by 90°.

[0016] As Figure 2 shown, in this embodiment, taking the FPGA as an example, the Hilbert transform module in the FPGA is implemented by an FIR filter. In this embodiment, the FIR filter is designed as an all-pass filter with a passband gain of 1, the phase characteristic is that the positive frequency is phase-shifted by -90°, the negative frequency is phase-shifted by 90°, and the order is designed as an even order. The signal output by the FIR filter is the imaginary part of the Hilbert transform analytic signal. Due to the fixed delay of the FIR filter, it is necessary to perform phase compensation on the original A-scan signal to obtain the real part of the Hilbert analytic signal. The phase compensation is achieved through delay, and the delay time is each clock cycle, and: Where: is the order of the FIR filter design; is the fixed delay generated by the register logic during the FIR filter design.

[0017] The signal after phase compensation and the signal after Hilbert transform enter the envelope extraction module at the same time. The envelope extraction module calculates the modulus of the Hilbert analytic signal, and then the envelope of the original A-scan signal can be obtained. The envelope signal is: Where: is the imaginary part of the Hilbert transform analytic signal; is the real part of the Hilbert analytic signal.

[0018] In the FPGA, squaring is implemented by a multiplier, and square root is implemented by the CORDIC algorithm.

[0019] Step 3: Align the A-scan signal with the envelope signal and take the absolute value to obtain the signal .

[0020] Specifically, in this embodiment, after delaying the original A-scan signal it is aligned with the obtained envelope signal , and after taking the absolute value, the signal is obtained.

[0021] Step 4: Set the envelope weight , , is an integer greater than or equal to 1; according to the ultrasonic scanning time axis, the envelope weight is segmented to control the envelope signals of different segments. Multiply the envelope signal and the signal by the envelope weights and respectively, then add them together, and shift to the right by bits to obtain the envelope signal after ultrasonic segmentation weighting.

[0022] Specifically, in this embodiment, the two signals and are simultaneously input into the segmented weight superposition module, and the internal structure of the segmented weight superposition module is as Figure 3 shown. is the set envelope weight. In order to facilitate the implementation of division operations through shifting in the FPGA, the set value in this embodiment is , The larger the value, the greater the envelope strength, then .

[0023] The module multiplies the signal by the weight, multiplies the signal by the weight, adds the multiplied signals together and then shifts to the right by 8 bits to obtain the weighted superposition signal.

[0024] In addition, can be segmented and set along with the time axis of the A-scan signal. For example, as Figure 4 shown, three segments are set. Assuming the sampling rate is 10 ns and the sampling length is 160 us, then it is divided into , and a total of three segments, and the weights of the three segments are set as follows: = 0, = 256, and = 100. The FPGA realizes the function of segmentally setting different envelope strengths by switching different weights in different time periods. Figure 5 is the effect of extracting the envelope by segment according to the Figure 4 setting.

[0025] The above-described embodiments are only preferred embodiments given to fully illustrate the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention. The protection scope of the present invention is subject to the claims.

Claims

1. An ultrasonic envelope segmented extraction method with controllable strength, characterized in that: The steps include: Step 1: The ultrasound device obtains the A-scan signal from the probe ; Step 2: Use Hilbert transform to obtain A-scan signal The envelope signal ; Step 3: Align the A-scan signal with the envelope signal and take the absolute value after alignment to obtain the signal ; Step Four: Set Envelope Weights , , is an integer greater than or equal to 1; segment the envelope weights according to the ultrasound scanning time axis to control the envelope signals of different segments; The envelope signal and signal Envelope weight and Multiply, add, and shift right The ultrasonic segment weighted envelope signal is obtained.

2. The method for extracting ultrasonic envelope segments with controllable intensity according to claim 1, wherein: In the second step, the envelope signal is as follows: Wherein: is the imaginary part of the Hilbert transform analytic signal; is the real part of the Hilbert analytic signal.

3. The method for extracting ultrasonic envelope segmented by intensity controllability according to claim 2, characterized in that: Hilbert transform to analyze the imaginary part of the signal The output is from an FIR filter, which is designed as an all-pass filter with a passband gain of 1, a phase characteristic of a positive frequency phase shift of -90°, a negative frequency phase shift of 90°, and an even order.

4. The method for extracting ultrasonic envelope segments with controllable intensity according to claim 3, characterized in that: Real part of Hilbert analytic signal By scanning the A signal Phase compensation is obtained by delay, and the delay time is is each clock cycle, and: Wherein: is the order of the FIR filter design; is the fixed delay generated by the register logic during the FIR filter design.

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