https://scholars.lib.ntu.edu.tw/handle/123456789/334056
標題: | Binary Code Design for High Frequency Ultrasound | 作者: | PAI-CHI LI | 公開日期: | 五月-2007 | 卷: | 54 | 期: | 5 | 起(迄)頁: | 947-955 | 來源出版物: | IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control | 摘要: | This paper proposes an approach to designing binary codes suitable for high-frequency applications of coded excitation in medical ultrasound. For a high-frequency ultrasound system, transmitting well-designed binary codes with a low sampling ratio (i.e., the bit rate divided by the transducer center frequency) is a practical way to improve the signal-to-noise ratio (SNR) because the challenge of implementing arbitrary-waveform generators for transmitting nonbinary codes increases with the frequency and the switching speed of square-wave pulsers are limited. One conventional approach designs codes using a base sequence that modulates wideband sequences up to the transducer passband. Because a major portion of codes is excluded as a candidate, codes designed using this approach typically need long compression filters for restoring the axial resolution, and they do not improve the SNR efficiently. In contrast, the approach proposed here searches all the codes that match the transducer passband; hence, the resultant codes exhibit better performance. The technique was tested using a bit rate of 50 MHz and a sampling ratio of 2. For a transducer with an ideal Gaussian frequency response with a center frequency of 25 MHz and a - 6 dB bandwidth of 15 MHz, the SNR for the same sidelobe extent was 1 to 6 dB higher for the codes designed using the proposed approach compared with those designed using the conventional approach. When a real transducer response with a center frequency of 26.4 MHz and a one-way - 6 dB bandwidth of 20.7 MHz was considered, the codes designed using the proposed approach were superior by 0.5 to 5 dB. Therefore, our approach is better than the conventional approach for designing binary codes for high-frequency ultrasound, with the results indicating that the moderate bit rate of 50 MHz will suffice when the ultrasonic center frequency is 25 MHz. © 2007 IEEE. |
URI: | http://scholars.lib.ntu.edu.tw/handle/123456789/334056 https://www.scopus.com/inward/record.uri?eid=2-s2.0-34250213280&doi=10.1109%2fTUFFC.2007.340&partnerID=40&md5=fc5ed6b195ec2b66d2264e1a10c3fcca |
ISSN: | 08853010 | DOI: | 10.1109/TUFFC.2007.340 | SDG/關鍵字: | Medical ultrasound; Nonbinary codes; Square-wave pulsers; Waveform generators; Frequency response; Signal to noise ratio; Square wave generators; Ultrasonics; Waveform analysis; Binary codes; algorithm; article; computer assisted diagnosis; echography; image enhancement; information processing; methodology; reproducibility; sensitivity and specificity; signal processing; Algorithms; Data Compression; Image Enhancement; Image Interpretation, Computer-Assisted; Reproducibility of Results; Sensitivity and Specificity; Signal Processing, Computer-Assisted; Ultrasonography |
顯示於: | 電機工程學系 |
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