| 摘要 |
An ultrasonic flow velocity measuring apparatus measures a transit time under the condition a synchronization of an ultrasonic signal having a modulated frequency by PN (pseudo noise) code of a diffusion band at a transmitting side is locked at a receiving side, and prevents an excessive measurement error exceeding allowable error range. If the installation positions of the ultrasonic transducers of upper and lower stream sides are moved, an ultrasonic transit time can be precisely measured by using a different signal series PN code without changing an electronic component and a program. In addition, the ultrasonic flow velocity measuring apparatus installs a plurality of ultrasonic transducers according to various distances from the bottom of a fluid passage, and accurately measures average flow velocity which is variable in response to the height in a curved fluid passage. Therefore, the ultrasonic flow velocity measuring apparatus can be effectively used for a larger river, a sluice open channel, or can be used for measuring a fluid quantity for gas and a water level and so on.
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