Acquisition System for the Arbitrary Pulse Width and Position Signals Application in Ultrasound

Study on the accuracy of the ultrasound velocity application for chemical process monitoring is presented. Cure degree of epoxy resins was monitored in order to establish the percentage of the final cure based on ultrasound velocity of longitudinal waves. Time of flight estimations by correlation processing were used to estimate the velocity. Sources of error in the velocity measurement and their influence in the sensitivity and accuracy of the results have been studied. In order to improve the accuracy and reliability of the measurements, the use of Spread Spectrum instead of conventional excitation signals have been evaluated. Experimental results indicate that random errors of propagation time estimation are lower than velocity fluctuation over the chemical process. Spread spectrum signals provide more reliable measurements.

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“…Acquisition of the signals was carried out using universal ultrasonic data acquisition system [13]. Bipolar pulser was used for excitation.…”

Section: Methodsmentioning

confidence: 99%

Assessment of Ultrasound Velocity Application for Chemical Process Monitoring

Svilainis

Rodríguez

Liaukonis

et al. 2015

ElAEE

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“…All the signals described above require arbitrary waveform signal generators, analog-digital converters and linear analog amplifiers, resulting in very expensive, costly and energy-inefficient equipment. On the contrary, rectangular signals are generated by simple switches, without the need for conversion, so binary excitation is more attractive and is widely used because: (i) it is simpler and the cost of the equipment is lower [42], [43], (ii) has higher efficiency, resulting in less temperature and longer battery life [44] and (iii) the size and weight of the equipment are lower, allowing portable equipment to be designed. Unfortunately, binary signals have certain disadvantages in the same direction as those we saw related to the type of excitation, that is, the irregularity of the spectrum, since chirp (unipolar or bipolar) signals add curly to the spectrum [45], and the lack of dynamic margin, as additional lateral lobes appear in the correlation [29].…”

Section: Introductionmentioning

confidence: 99%

On the Optimization of Spread Spectrum Chirps Into Arbitrary Position and Width Pulse Signals. Application to Ultrasonic Sensors and Systems

et al. 2022

Self Cite

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This work presents in detail a new method for the optimization of rectangular spread spectrum excitation signals for its use in simple and low-cost ultrasonic pulsers, but that could be extended to other applications based on spread spectrum signals. Starting from rectangular linear frequency modulated (RLFM) chirps, it uses the transfer function of the transmitted signal and received echoes from reference specimens to iterate through a recursive algorithm to obtain arbitrary position and width pulse (APWP) signals with the desired bandwidth, maximizing the energy and the flatness of the spectrum, and enhancing the resolution and dynamic range of conventional chirp excitation signals. This optimization procedure can be repeated for any transducer and material, so that it achieves the best performance in each experimental environment. Such characteristics are ideal for Time-of-Flight estimation, imaging, and applications in which spectral regularity is needed, such as the Split Spectrum Processing (SSP) algorithm, which is used as example to test the performance of the proposed excitation signals. It also allows to specify and change the bandwidth reducing the need to change the transducers. The method is tested with different transducers (2 and 5 MHz focused transducers) and complex composite materials (aluminum-carbon aviation composite and high porosity GFRP composite) in immersion setup for imaging applications using SSP algorithm.INDEX TERMS Ultrasound, Spread Spectrum, chirp, arbitrary position and width pulses, Split Spectrum Processing, non destructive testing.

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“…For most devices, they are only capable of transmitting rectangular pulses with either a high or low level. Therefore, as a compromise, the option is to transmit rectangular linear frequency-modulated (RLFM) signals [74][75][76][77], also known as pseudo-chirp signals, as shown in Figure 10. However, transmitting such alternative signals does come with certain drawbacks.…”

mentioning

confidence: 99%

Coded Excitation for Ultrasonic Testing: A Review

Weng,

Gu,

Jin

2024

Sensors

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Originating in the early 20th century, ultrasonic testing has found increasingly extensive applications in medicine, industry, and materials science. Achieving both a high signal-to-noise ratio and high efficiency is crucial in ultrasonic testing. The former means an increase in imaging clarity as well as the detection depth, while the latter facilitates a faster refresh of the image. It is difficult to balance these two indicators with a conventional short pulse to excite the probe, so in general handling methods, these two factors have a trade-off. To solve the above problems, coded excitation (CE) can increase the pulse duration and offers great potential to improve the signal-to-noise ratio with equivalent or even higher efficiency. In this paper, we first review the fundamentals of CE, including signal modulation, signal transmission, signal reception, pulse compression, and optimization methods. Then, we introduce the application of CE in different areas of ultrasonic testing, with a focus on industrial bulk wave single-probe detection, industrial guided wave detection, industrial bulk wave phased array detection, and medical phased array imaging. Finally, we point out the advantages as well as a few future directions of CE.

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Acquisition System for the Arbitrary Pulse Width and Position Signals Application in Ultrasound

Cited by 3 publications

References 0 publications

Assessment of Ultrasound Velocity Application for Chemical Process Monitoring

Assessment of Ultrasound Velocity Application for Chemical Process Monitoring

On the Optimization of Spread Spectrum Chirps Into Arbitrary Position and Width Pulse Signals. Application to Ultrasonic Sensors and Systems

Coded Excitation for Ultrasonic Testing: A Review

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