SIGNAL PROCESSING METHOD OF ELECTROMAGNETIC FLOWMETER

摘要

PURPOSE:To remove influence from external noises by using either a comparison voltage signal sampled or the preceding comparison voltage signal for computation of flow rate according to the difference therebetween. CONSTITUTION:The exciting current varies with a switch 10 responding to a control signal and a voltage is sampled in proportion to a flow rate due to a transmitter made up of electrodes 3a and 3b and the like provided on an exciting coil 1 and an insulated conduit 2. A division is done between this voltage and a comparison voltage synchronously sampled through a resistance 5 through a CPU11 and a flow rate signal is generated from an output circuit 12. This comparison voltage is compared with the precedong comparison voltage and when the difference is above a specified value, hence judged that external noises overlap the comparison voltage, the CPU11 perform a division using the preceding comparison voltage memorized in a memory 16 to determine the flow rate. This creates a signal processing circuit of an electromagnetic flowmeter which can prevent effect of external noises in substance.