• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.637-638
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• 2009

• Progress in Medical Physics
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• v.5 no.1
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• pp.25-39
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• 1994

To measure the velocity of heart wall and local flow transctaneously in blood vessels, we have developed a single channel 3.1 MHz pulsed ultrasonic Doppler velocity meter. Ultrasound pluse width and repetition frequency (PRF) used in the velocity meter is 1 ${\mu}$sec 6kHz reapectively, and the Doppler shift of the backscattered echo signal is sensed in a phase detector by coherent demodulation method. From the output of the phase detector, the Doppler signal corresponding to the mean velocity of acoustic wave scatterers over a small region is obtained by using a range gate, sample holder and band-pass filter. Mean frequency of Doppler signal is estimated by zero-crossing counter and the instantaneous velocity of scatters is displayed as a function of time. It is possible to estimate velocity profile, volume flow and flow acceleration of vessels in man if the number of channels and range resolution in increased.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.5
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• pp.33-40
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• 1984

In the conventional pulsed doppler system, gated CW is used to excite a ultrasonic transducer so that a group of linear RF amplifiers are required to excite a ultrasonic array transducer in the scanning pulsed doppler system. A pulsed doppler system without linear high voltage RF amplifiers, which excites the transducer impulsively, is studied theoretically and experimentally. In this paper, an experimental 8-channel pulsed doppler system is implemented, which uses quadrature defection to detect the direction of motion and can compensate the attenuation effect. The designed pulsed doppler system shows the possibility of real time multichannel doppler flow meter.