Research on signal processing method of vortex flow meter

A new signal processing circuit of vortex flow meter based on variable gain amplifier and digital signal processor(DSP) unit is designed. It measures the range and frequency of the vortex flow meter output signals by the analog to digital converter (A/D) of the DSP on real time, and the gain of the variable gain amplifier is controlled by the digital to analog converter(D/A), then the relative stable range of the sensor output signals can be obtained. Due to the frequency characteristic of the vortex flow meter output signals, a FIR filter arithmetic based on the DSP is designed, it effectively inhibits strong noise in the output signals. And then the frequency of the filtered signal and the flux of the liquid are calculated by the DSP. The experimental results show that the complex amplifier circuit due to the large variable range of the vortex flow meter output signals and the discontinuous problem of the signals are solved by the variable gain amplifier. The noise of the signals is effectively restrained and the flow rate is calculated precisely because the DSP is adjusted for digital filtering and frequency calculation.