High-resolution ultrasonic pulse-echo measurement is discussed. For higher time resolution, a sensitivity-compensated (SC) signal and a method of band expansion using linear prediction (LP) processing have been proposed. Moreover, two-dimensional direction measurement calculated from the difference in distances derived using the SC signal has been studied. Because a small error in distances will result in a large error in the direction result, higher accuracy of distance measurement is required. In this paper, the efficiency of band expansion using LP processing with an autoregressive model is discussed for two-dimensional direction measurement. The comparison results show that by using the band expansion method, the compressed pulse width is shortened to about 18% of its original value and the accuracy of direction measurement is improved using the higher-time-resolution signal.
2017 by The Acoustical Society of Japan