| 摘要 |
<p>PURPOSE:To measure pulse Doppler with a high signal-to-noise ratio by obtaining the correlation between phase signals respectively having a specific time interval out of phase signals successively sampled at time intervals equal to the wave sending intervals of an ultrasonic wave pulse, obtaining a phase difference vector, and calculating a speed from the angle of the phase difference vector. CONSTITUTION:Out of the phase signals successively sampled at a time interval T equal to the wave sending interval of the ultrasonic wave pulse, the correlation between the phase signals respectively having the time interval of nT (n: an integer >=2) is obtained, the phase difference vector is obtained, and the speed is calculated from the angle of the phase difference vector. The ultrasonic wave pulse sent toward an arbitrary part in a heart at the wave sending interval T is reflected by a blood flow and received. When the received signal is inputted to an input terminal 100, a Doppler signal is detected by a phase comparator 1. The detected signal is made into time series data by an A/D converter 2. An output omegad of a divider 12-1 and a Doppler frequency (the output of a divider 12-2) omegad' obtained by an added part 413 are obtained, either of the outputs is selected by a discriminator 13, and the selected output is outputted.</p> |
