HYDROACOUSTICS
ANNUAL JOURNAL |
START | NEW VOL 20 | SEARCH | STATISTICS | PAS - GDANSK DIVISION |
pp. 173-182, vol. 7, 2004 Andrzej Nowicki Department of Ultrasound, Institute of Fundamental Technological Research, Polish Academy of Sciences, Warsaw, Poland Igor Trots Department of Ultrasound, Institute of Fundamental Technological Research, Polish Academy of Sciences, Warsaw, Poland Wojciech Secomski Department of Ultrasound, Institute of Fundamental Technological Research, Polish Academy of Sciences, Warsaw, Poland Jerzy Litniewski Department of Ultrasound, Institute of Fundamental Technological Research, Polish Academy of Sciences, Warsaw, Poland Key words: Abstract: The issue of maximizing penetration depth with concurrent retaining or enhancement of image resolution constitutes one of the time invariant challenges in ultrasound imaging. Concerns about potential and undesirable side effects set limits on the possibility of overcoming the frequency dependent attenuation effects by increasing peak acoustic amplitudes of the waves probing the tissue. To overcome this limitation a pulse compression technique employing 16 bits Complementary Golay Code (CGS) was implemented at 4 MHz. In comparison with other, earlier proposed, coded excitation schemes, such as chirp, pseudo-random chirp and Barker codes, the CGS allowed virtually side lobe free operation. Computer simulation results for CGS pulse compression are presented. Next three different methods and algorithms used to calculate the pairs of Golay sequences of the different length are described. Experimental results are presented in the form, which in clear way illustrates the resolution, signal penetration and contrast dynamics of ultrasonic images obtained by using Golay coded excitation.
Download: Fulltext PDF, BibTeX © Polish Acoustical Society - Gdansk Department, Polish Academy of Sciences. This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported. (CC BY-NC-SA 3.0) |