Abstract：
:In this paper the study of frequency-dependent ultrasonic attenuation in strongly heterogeneous materials is addressed. To determine the attenuation accurately over a wide frequency range, it is necessary to have suitable excitation techniques. Three kinds of transmitted signals have been analysed, grouped according to their bandwidth: narrowband and broadband signals. The mathematical formulation has revealed the relation between the distribution of energy in their spectra and their immunity to noise. Sinusoidal and burst signals have higher signal-to-noise ratios (SNRs) but need many measurements to cover their frequency range. However, linear swept-frequency signals (chirp) improve the effective bandwidth covering a wide frequency range with a single measurement and equivalent accuracy, at the expense of a lower SNR. In the case of highly attenuating materials, it is proposed to use different configurations of chirp signals, enabling injecting more energy, and therefore, improving the sensitivity of the technique without a high time cost. Thus, if the attenuation of the material and the sensitivity of the measuring equipment allows the use of broadband signals, the combination of this kind of signal and suitable signal processing results in an optimal estimate of frequency-dependent attenuation with a minimum measurement time.
journal_name
Ultrasonicsjournal_title
Ultrasonicsauthors
Genovés V,Gosálbez J,Carrión A,Miralles R,Payá Jdoi
10.1016/j.ultras.2015.09.007subject
Has Abstractpub_date
2016-02-01 00:00:00pages
345-52eissn
0041-624Xissn
1874-9968pii
S0041-624X(15)00230-9journal_volume
65pub_type
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