Method and system for eliminating direct-current deviation of ultrasonic echo signal

Abstract

The invention discloses a method for eliminating direct-current deviation of an ultrasonic echo signal. The method comprises steps that S1, a chip controls a transmitting module to divide the transmitted ith scanning line into an odd number group and an even number group, one group of transmitting lines is controlled to transmit positive polarity or negative polarity pulses, the other group of transmitting lines is controlled to transmit reverse phase pulses, i = 1, 2,..., M, and M is a positive integer larger than or equal to 2; S2, a receiving module receives the pulses transmitted in the step S1, and the two groups of transmitted echo signals are summed to obtain harmonic signals; S3, the harmonic signals obtained on the M scanning lines are spliced to obtain a final harmonic signal; and S4, the received pulse waves are analyzed and processed by the chip to obtain a defect graph of the to-be-detected workpiece, and the defect graph is displayed through a display. The method is advantaged in that purposes of eliminating direct-current deviation and enhancing the signal-to-noise ratio are both achieved, and complexity of ultrasonic echo signal processing is lowered.

Description

technical field [0001] The invention relates to the field of ultrasonic detection, in particular to a method and system for eliminating DC deviation of ultrasonic echo signals. Background technique [0002] Ultrasonic testing is a detection method for testing internal defects of materials by using the difference in acoustic properties of materials and their defects to the energy changes in the reflection of ultrasonic wave propagation and penetration time. [0003] Existing ultrasonic industrial detection detection and transmission circuits usually require a large dynamic range, and may work in the receiving and amplifying channel in the amplification range of about -40db to +80db. In such a wide range of adjustments, the DC Deviation elimination often adopts the method of capacitor DC blocking at the last stage, but this mode still cannot eliminate the DC deviation of ADC, and because of the existence of DC blocking capacitors, the transmitted pulse energy is blocked, so th...

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Problems solved by technology

[0003] Existing ultrasonic industrial detection detection and transmission circuits usually require a large dynamic range, and may work in the receiving and amplifying channel in the amplification range of about -40db to +80db. In such a wide range of adjustments, the DC Deviation elimination often adopts the method of capacitor DC blocking at the last stage, but this mode still cannot eliminate the DC deviation of ADC, and because of the existence of DC blocking capacitors, the transmitted pulse energy is blocked, so the weak echo signal in front will be caused by If the blockage time is too long, the detection near the surface cannot be implemented. There are also DC coupling amplification modes, and digital dynamic adjustment of the DC bias of the front stage, but this requires more complex control circuits, and the ability to suppress temperature drift is also affected. limit

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