Power-spectrum-analysis-based signal processing system of vortex flowmeters

A power-spectrum-analysis-based signal processing system was developed for vortex flowmeters. This system consists of a digital signal processor (DSP), an analog input part, an output part, a keyboard input circuit, a guard circuit, a serial communication interface, and software. The sensor output signals are processed digitally using the power spectrum analysis based on fast Fourier transform, and the signal frequency reflecting the flow rate is calculated. With the change of sampling frequency and the spectrum correction, the measurement accuracy of the system is improved and the volumetric flow rate is obtained accurately. By means of adopting a DSP and processing signals while sampling data, the signal processing in real time is ensured. The experiments, including tests of the charge amplifier and signal processing system, and calibration of the vortex flowmeter, show that the performance indexes of the digital processing system are better than those of the conventional instruments for vortex flowmeters in the measurement accuracy, the turn-down ratio, and the adaptability.