Ultrasonic flowmeters are instruments that measure flow by detecting the effect of fluid flow on ultrasonic beams (or ultrasonic pulses), in order to solve some difficult measurement problems. Ultrasonic flowmeter, which integrates computer and sensor technology, combines the research results of acoustics with modern electronic technology, and can be used for the measurement of various liquids.
In the ultrasonic flowmeter measurement system, there are many types of noise source substances. Such as:
(1) The large electric and magnetic field interference that may exist in the installation environment of the flowmeter;
(2) The noise close to the ultrasonic signal brought by the water pump when it is installed close to the water pump;
(3) The communication system carried by the operator;
(4) Higher harmonics in the power supply;
(5) Noise interference caused by the high-frequency crystal oscillator on the circuit board.
For the noise interference source from the outside, the main method is to reduce the sensitivity of the circuit to noise, reduce the noise pickup, and cut off the noise coupling path. For the noise source from the inside of the system, such as the circuit board, the signal ground , digital ground separation, multi-point grounding, reasonable wiring method to solve.
A noise problem must have three elements. First, there must be a noise source; second, there must be a noise-sensitive receiver; third, there must be a coupling path that transmits the noise from the source to the receiver. Therefore, to solve the noise problem, we must start from these three aspects.