| 摘要 |
Transmitting and receiving circuit for an ultrasonic flowmeter, comprising at least two ultrasonic transducers arranged for the transmission and receipt of ultrasonic signals in opposite directions across a measuring distance, a signal source for controlled production of electrical signals for transmission to the ultrasonic transducers and detection means for deriving transmission time measurements, used to calculate the flow, measuring of which is desired. The transmitting and receiving circuit includes an amplifier with a first inverting input terminal for connection to an ultrasonic transducer, a second non-inverting input terminal for connection to the signal source, an output terminal for connection with the detection means, and a feedback connection between the output terminal and the first input terminal. Switching means is provided for alternating functional connection of one of the ultrasonic transducers with the first input terminal provides a simplified circuit arrangement with a high degree of immunity towards component tolerances and different temperature coefficients. |
