Ultrasonic attenuation measurements at very high SNR: Correlation, information theory and performance

Challis, Richard; Ivchenko, Vladimir; Al-Lashi, Raied

Abstract

This paper describes a system for ultrasonic wave attenuation measurements which is based on pseudo-random binary codes as transmission signals combined with on-the-fly correlation for received signal detection. The apparatus can receive signals in the nanovolt range against a noise background in the order of hundreds of microvolts and an analogue to digital convertor (ADC) bit-step also in the order of hundreds of microvolts. Very high signal to noise ratios (SNRs) are achieved without recourse to coherent averaging with its associated requirement for high sampling times. The system works by a process of dithering-in which very low amplitude received signals enter the dynamic range of the ADC by 'riding' on electronic noise at the system input. The amplitude of this 'useful noise' has to be chosen with care for an optimised design. The process of optimisation is explained on the basis of classical information theory and is achieved through a simple noise model. The performance of the system is examined for different transmitted code lengths and gain settings in the receiver chain. Experimental results are shown to verify the expected operation when the system is applied to a very highly attenuating material-an aerated slurry. © Published under licence by IOP Publishing Ltd.

Citation

Challis, R., Ivchenko, V., & Al-Lashi, R. (2012, August). Ultrasonic attenuation measurements at very high SNR: Correlation, information theory and performance. Presented at 11th Anglo-French Physical Acoustics Conference (AFPAC 2012), Brighton, UK

• Presentation Conference Type: Conference Paper (published)
• Conference Name: 11th Anglo-French Physical Acoustics Conference (AFPAC 2012)
• Start Date: Aug 18, 2012
• End Date: Jan 20, 2012
• Online Publication Date: Aug 1, 2013
• Publication Date: Aug 1, 2013
• Deposit Date: Apr 3, 2014
• Publicly Available Date: Apr 3, 2014
• Journal: Journal of Physics: Conference Series
• Print ISSN: 1742-6588
• Electronic ISSN: 1742-6596
• Publisher: IOP Publishing
• Peer Reviewed: Peer Reviewed
• Volume: 457
• Issue: 12004
• Pages: 012004
• DOI: https://doi.org/10.1088/1742-6596/457/1/012004
• Keywords: General Physics and Astronomy
• Public URL: https://nottingham-repository.worktribe.com/output/1003596
• Publisher URL: http://m.iopscience.iop.org/1742-6596/457/1/012004?fromSearchPage=true