| 摘要 |
PURPOSE:To remove a clutter component, by a method wherein the clutter component contained in an orthogonal Doppler signal is extracted by a culture component removing signal generating circuit and a clutter component removing signal is generated from said clutter component and an orthogonal reference signal to be inputted to the first adder and added to the clutter component contained in a received echo signal. CONSTITUTION:The clutter component removing signal synthesized on the basis of an orthogonal Doppler signal is inputted to the first adder 4 and the clutter component contained in an echo signal is added to the clutter component removing signal to be set off to disappear. Therefore, the clutter component is not almost contained in the output on and after the output of the first adder 4. As a result, the gain of an amplifier 5 can be made large and, even when this system is used in an HPRF method for observing the weak blood flow signal of a deep part containing many clutter components, blood flow can be well measured. The Doppler signal Edx, Edy outputted from a sample holding circuit 11 pass through a high-pass filter 13 to remove a clutter component having further high frequency and subsequently analyzed in frequency by a frequency analyzer 14 to be displayed on a display part 15.
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