| 摘要 |
PURPOSE:To provide the ultrasonic Doppler rheometer with which the sensitivity does not degrade and good Doppler signals are obtainable even if a gate exits in the deep part of a testee body. CONSTITUTION:The gate through which the phase detection signals of the echo signals from the inside of a living body are passed is bisected by analog switches 4a to 4d. The respective phase detection signals are passed through integrators 5a to 5d, sample-hold circuits 6a to 6d, high-pass filters 7a to 7d and are converted to digital signal by A/D conversion circuits 8a to 8d. The phases of the signals from the A/D conversion circuits 8a to 8d are shifted by phase shifters 9a, 9b. The signals matched in the directions of vectors are added by adders 10a, 10b. The added signal is subjected to a frequency analysis in a frequency analyzer 11. The negation of the signals by each other is prevented by dividing the gate. |
