Investigation of Sound Speed Errors in Adaptive Beamforming

Iben Kraglund Holfort, Fredrik Gran, Jørgen Arendt Jensen

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Abstract

Previous studies have shown that adaptive beam-formers provide a significant increase of resolution and contrast, when the propagation speed is known precisely. This paper demonstrates the influence of sound speed errors on two adaptive beamformers; the minimum variance (MV) beamformer and the amplitude and phase (APES) beamformer. Simulations of a single point target are carried out in Field II, and a percentage error is applied on the speed of sound. As the error increases, MV and APES provide amplitude drops of 17 dB and 3 dB on the signal strength. Two approaches to overcome this amplitude drop is proposed; diagonal loading (DL) and forward-backward (FB) averaging of the covariance matrix. The investigations show that DL provides a slightly decreased resolution and amplitude compared to FB. It is noted that APES provides more robust estimates than MV at the mere expense of a slight decrease of resolution. From the investigations, it is concluded the performance of the adaptive beamformers are not outperformed by the conventional delay-and-sum beamformer.
Original languageEnglish
Title of host publicationProceedings of the IEEE International Ultrasonics Symposium
PublisherIEEE
Publication date2008
Pages1080-1083
ISBN (Print)978-1-4244-2428-3
DOIs
Publication statusPublished - 2008
Event2008 IEEE International Ultrasonics Symposium - Beijing, China
Duration: 2 Nov 20085 Nov 2008
http://ewh.ieee.org/conf/ius_2008/

Conference

Conference2008 IEEE International Ultrasonics Symposium
CountryChina
CityBeijing
Period02/11/200805/11/2008
Internet address

Bibliographical note

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