FILTER CIRCUITS FOR REDUCING VIBRATION SENSITIVITY IN VORTEX SHEDDING FLOWMETER SIGNAL GENERATORS

摘要

A notch filter arrangement for reducing vibration noise in a vortex shedding flowmeter circuit is disclosed which utilizes a plurality of sequentially closable switches. The plurality of switches are all closed during a single period of the vibration signal fundamental frequency. Each switch is connected in series to a capacitor which is connected to the output signal of a vortex sensor so that the instantaneous average voltage of the vibration signal during any increment of time is subtracted from the vortex shedding frequency signal to produce a noise reduced signal.