Signal acquisition and processing method for capacitive electromagnetic flowmeter

Abstract

A kind of signal acquisition circuit and the related signal processing method of the capacitance electromagnetic flowmeter were introduced. The circuit can eliminate the influence of distributed capacitance on the input impedance of the operational amplifier, and greatly improve the input impedance of the detection circuit to overcome the disadvantage of high signal source impedance. The rotating capacitor filter is a signal processing method based on the phase-sensitive detection technology. It can extract the weak signal from the strong and wide-band background noise, so it is very suitable for the processing of capacitive electromagnetic flow signals. Through the comparison of the signal amplitude obtained at different flow rates and the comparison of signal spectrum components before and after the filter, the effectiveness of the bootstrap signal acquisition circuit and rotating capacitor filtering method is verified.

Keywords

• Bootstrap circuit
• Capacitive coupling
• Electromagnetic induction
• Fluid flow measurement
• Lock-in amplifier