Multilevel modulation ultrasonic encoding single excitation method based on Golay complementary convolutional codes

Abstract

The invention discloses a multilevel modulation ultrasonic encoding single excitation method based on Golay complementary convolutional codes. The method includes the steps that a multi-element code C=A*B is generated for single encoding excitation by means of convolution operation of an orthocomplementation Golay (A,B) code binary sequence; amplitude modulation and phase modulation of the multi-element code C are achieved through an encoding controller, code element symbols are mapped into electric pulse signals with certain phases and amplitudes, and an ultrasonic probe is excited; excitation conversion factor conversion from C to A and from C to B is conducted on echo signals subjected to encoding excitation, two paths of echo signals are formed, the C code excited once indirectly generates the effect achieved by independent dual excitation of the A code and the B code, and the quasi single excitation technology is formed; the two paths of echo signals are subjected to pulse compression, and ideal encoding is achieved through vector synthesis; finally, complementary Golay (A,B) with the code length Lc being 8 is subjected to encoding excitation and decoding, the functions are simulated, and the encoding excitation effect is verified through FPGA hardware. Compared with a traditional method, echo gain and excitation efficiency are indirectly improved, and the method also has great advantages in the aspects of signal-to-noise ratio, flexibility and implementation performance.

Description

technical field [0001] The invention relates to a multi-element modulation ultrasonic coding single excitation method based on Golay complementary convolution code. Background technique [0002] The coding excitation technology of the ultrasonic phased array system is basically similar to the traditional single pulse excitation technology. It excites the ultrasonic probe by sending electric pulses with a certain phase, amplitude, and pulse width to realize electro-acoustic signal conversion and scan the inside of the workpiece under test. The echo signal is collected and image reconstruction is carried out for analysis. The differences are as follows: the microcosmic performance is that the number of pulses transmitted each time, the phase and the processing scheme of the received echo are inconsistent, and the macroscopic results show that: under the same hardware conditions, the coding excitation technology (software means) can get the same as a single pulse. The same hor...

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Problems solved by technology

For example, Jinhyoung Park (2010) of the University of California, University of California (2010) used Golay code excitation technology and a 6dB bandwidth amplifier to achieve ripple within 4dB in the 10-110MHz frequency band, reflecting excellent performance; University of Science and Technology of China (2010) used Chirp signal Modulate the Golay complementary code excitation to increase the medical ultrasound transmission depth and anti-interference ability; On the one hand, it reduces the scanning efficiency of the ultrasonic phased array instrument, on the other hand, in some dynamic scanning processes, there will be a problem that the position changes and cause the two transmissions and receiving waveforms to be inconsistent, which will affect the decoding effect.

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