| 摘要 |
PURPOSE:To perform measurement having separating and resolving power using a continuous wave by arranging a transmitting transducer and a receiving transducer on the surface of the body in a separated state so that transmitting beam and receiving beam cross each other only within a region to be observed. CONSTITUTION:A transmitting transducer 44 and a receiving transducer 43 are arranged on the surface of a living body 41 so that the centers of transmitting and receiving beams cross each other in a blood vessel 42 to be measured. The output of a continuous wave generator 46 is multiplied by the signal obtained by shifting said output by a pi/2 phase shifter 22 in multipliers 21a, 21b. The outputs of the multipliers 21a, 21b are applied to low-band-pass filters 23a, 23b to remove the high frequency components to become the same phase output and orthogonal phase output. These outputs are converted to digital signals by A/D converters 24a, 24b while the digital signals are converted in frequency by a fast Fourier transform circuit 25 to measure a blood flow speed.
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