Vortex Signal Processing Based on Frequency Tracing Filtering

To improve the measurement accuracy at low flow rate, a comprehensive method of vortex flow signal processing based on frequency tracing filtering is introduced in this paper, which combines the FFT spectrum estimation in frequency domain with the adaptive filtering in time domain. The implementation of the measurement system is discussed. The system can achieve the real-time tracing and measuring of vortex frequencies through proper adjustment of the filter parameters, waveforms transform and pulse capture. The filter parameters are adjusted in the light of the key signal frequencies obtained by FFT spectrum analysis. Moreover, the mechanisms of intelligent decision and frequency feedback are adopted in the system. The tests based on the FFT-tracing method and the frequency-tracing feedback method were accomplished with low-rate vortex signal produced by an NI signal generator (LabWindows / CVI programming). The test results showed that the accuracy of this measurement system was improved at low flow rate.