| 摘要 |
PURPOSE:To make measurement with high accuracy by optimum S/N and resolving power according to the distance up to a measuring section by setting the time after the emission of ultrasonic pulses and before arriving at the sampling of reflected waves and adjusting the pulse width of the ultrasonic pulses according to the distance up to an assigned section. CONSTITUTION:This device is so constituted as to set the time after the emission of the ultrasonic pulses and before the sampling of the reflected waves according to the distance up to the assigned section by a sample position setter 33 and a 2nd progrommable counter 34 and to regulate the pulse width in proportion to the above- mentioned set time by a repetitive frequency setter 31, the 1st and 2nd progrommable counters 32, 36, a sample position setter 33, and a read-only memory 35. The pulses with the pulse width proportional to the set time before the taking of the reflected waves corresponding to the distance up to the measuring section are then emitted and the reflected waves are sampled at the timing based on the above-mentioned set time. The pulse width is increased and the S/N is expanded with an increase in the distance up to the measuring section. The flow velocity of blood is measured by the optimum S/N and resolving power according to the distance up to the measuring section. |
