유속측정을 위한 위상분석법을 이용한 펄스 도플러 기법에 관한 연구

Abstract

Most Doppler flowmeters on the maket today estimate the flow rate more accurately than methods based on level measurement alone, but do not have the accuracy of magnetic-inductive and Venturi flowmeters. More recently, pulsed doppler technology has been introduced for measuring flow. Pulsed Doppler avoids some important limitations and accuracy problems that continuous wave Doppler flowmeters are plagued with. The pulsed Doppler output spectrum of a moving target is achieved by utilizing the Doppler principle. The Doppler ultrasound system was designed and used to detect information on flow motion. Most diagnostic ultrasound system is to separate moving target echoes from relatively stationary target echoes. When we observed a moving target using a suitably configured Doppler system, It is shown that for a single approaching target the output spectrum which Doppler system produces is time-dilated replica of the received echo signal. On the other hand, for a receding target the output is time inverted as well as dilated. Doppler output spectra for moving target are presented theoretically, the results are used to calculate an expression for the output spectra of a pulsed Doppler system, and confirmed experimentally.