DocumentCode :
3018945
Title :
Investigation of sound speed errors in adaptive beamforming
Author :
Holfort, Iben Kraglund ; Gran, Fredrik ; Jensen, Jergen Arendt
Author_Institution :
Dept. of Electr. Eng., Tech. Univ. of Denmark, Lyngby
fYear :
2008
fDate :
2-5 Nov. 2008
Firstpage :
1080
Lastpage :
1083
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.
Keywords :
acoustic wave velocity; array signal processing; biomedical ultrasonics; covariance matrices; image resolution; medical image processing; adaptive beamforming; amplitude-and-phase beamformer; covariance matrix; diagonal loading; forward-backward averaging; image resolution; medical ultrasound imaging beamforming; minimum variance beamformer; signal strength; single point target; sound speed errors; Acoustic imaging; Acoustic propagation; Array signal processing; Biomedical imaging; Covariance matrix; Focusing; Robustness; Sensor arrays; Signal resolution; Ultrasonic imaging;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Ultrasonics Symposium, 2008. IUS 2008. IEEE
Conference_Location :
Beijing
Print_ISBN :
978-1-4244-2428-3
Electronic_ISBN :
978-1-4244-2480-1
Type :
conf
DOI :
10.1109/ULTSYM.2008.0260
Filename :
4803300
Link To Document :
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