Ultrasonic Flaw Detection Using Overflow-Selected Multi-ADC Channels
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Solution Overview
Problem
Existing ultrasonic flaw detectors face challenges with complex analog front ends, leading to calibration difficulties, reliability issues, and inconsistent results due to input impedance matching, gain nonlinearities, back wall attenuation, and DC offset errors, which affect the detection of internal structural faults in materials.
Innovation Solution
A high dynamic range analog to digital conversion system with multiple A/D converter channels that eliminate the need for a Variable Gain Amplifier (VGA) circuit, allowing for simpler circuitry, reduced calibration time, and more accurate inspection results by adjusting sample times, preventing signal distortion, and compensating for frequency response and offset errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple A/D converter channels are used to extend dynamic range, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent divides the signal processing into multiple A/D converter channels, each handling different signal amplitude ranges. The first channel processes larger amplitude signals while the second channel processes smaller amplitude signals, allowing each converter to operate within its optimal range and thereby extending the overall dynamic range of the system.
Solution Approach 2:
The patent introduces a signal routing mechanism that acts as an intermediary between the transducer and the A/D converters. This routing system directs signals to appropriate channels based on their amplitude characteristics and combines the results, effectively managing the complexity of multiple converters through intelligent signal distribution and integration.
2Adaptability or versatility
If analog circuits are switched in and out of signal path to adjust gain, then adaptability is improved, but reliability deteriorates due to calibration issues and DC offset errors
Solution Approach 1:
The patent replaces the mechanical switching of analog circuits with a digital signal processing approach. Multiple A/D converter channels with different gain characteristics are used instead of switching analog amplifiers, eliminating the reliability issues associated with analog switching while maintaining the ability to adjust gain through digital selection of appropriate channels.
Solution Approach 2:
The patent changes the approach from dynamically switching analog parameters to using fixed-parameter digital channels. Each A/D converter channel has a predetermined gain setting, and the system adapts by selecting the appropriate channel based on signal amplitude, thereby achieving gain adjustment without the calibration and stability issues of switched analog circuits.
3Measurement precision
If time varied gain function is used to compensate back wall attenuation, then measurement precision is improved, but device complexity increases due to limited gain range and rate of change
Solution Approach 1:
The patent segments the time-varied gain function into discrete channels, each optimized for specific time ranges and signal amplitudes. By dividing the detection timeline into segments handled by different A/D converter channels, the system achieves comprehensive back wall attenuation compensation without requiring a single complex continuously variable gain circuit.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides more accurate, consistent, and easily readable inspection results by extending the dynamic range of the A/D converter circuit, reducing signal skew and amplitude matching errors, and minimizing the impact of DC offset errors, thereby improving the detection of internal structural faults in materials.
Implementation Method 1
transmitting ultrasonic pulses to a target object and analyzing echo signals detected from the target object
Implementation Method 2
a high dynamic range analog to digital conversion system
Data Source
AI summary
A method and apparatus for effecting ultrasonic flaw detection of an object processes an echo signal received from the object being tested in at least three signal channels, wherein the echo signal is scaled to different degrees along each channel to increase and extend the dynamic range of an associated A/D converter system, in a manner which dispenses with the need for using numerous analog high pass and low pass filters and a variable gain amplifier. This reduces complexity and avoids performance limitations. The digital to analog converters sample the differently scaled input signal and a selection circuit selects the output of the digital output obtained from that analog to digital converter which has the highest gain, but which has not overflowed. The digital outputs are seamlessly merged to produce an output that can be displayed as a scan display which shows the location of faults.