| Summary: | 碩士 === 國立臺灣海洋大學 === 電機工程學系 === 92 === This thesis uses beamforming in ultrasonic imaging. Beamforming is a kind of spatial filtering, which strengthen the signal of steering direction and suppress the interference of other directions. Nevertheless, there are a lot of questions have to overcome, such as poor directivity leads to coarse resolution; the noise is unable to reject efficiently due to high side lobe. Hence, in order to design the high performance of ultrasonic array, primary task is research of ultrasonic array, which can influence all kinds of parameters on beam power pattern (BPP).
In the situation of lower number of array element and lower circuit complexity, it is essential to raise center frequency or extend interelement spacing for reduction main’s width. Unfortunately, the grating lobe will be occurred when interelement spacing is larger than . Hence, we use the wide-band beamforming technology to suppress grating lobe. Besides, we design architecture of Mill’s cross array to equal 2D array and create tree dimension imaging. We attempt to reach high resolution and high quality ultrasonic imaging with sparse array.
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