Research On Digital Signal Processing Of Vortex

Vortex flowmeter is an important member in flow measurement field due to its no moving components, insensitivity to media, low pressure loss and so on. However, for a long time, designers and users are fazed by some application problems, such as the vibration noise, measurement of low flow rate and so on.In this paper, through the analysis of the former researches, the various methods of time domain, frequency domain and time-frequency analysis are compared and improved, the practical digital signal processing technique of the vortex flowmeter is studied completely. Moreover, all of them are verified by real signal data. The key points include:1. The vortex signal model which consists of additive noise and multiplicative noise is constructed in order to evaluate the digital signal processing methods;2. Comparing with various algorithms of time domain, the Rife spectrum estimation algorithms based on the phase criterion is proposed. It can satisfy precision of spectrum estimation and almost not increase calculating times.3. Comparing with the algorithms of time-frequency analysis, Wavelet analysis method is perfected in process of filtering and frequency detecting. The symletA wavelet is selected to be the original wavelet; the number of decomposition levels is decided by ratio of approximation coefficients standard deviation and detail coefficients standard deviation; the frequency is counted by the new peak search method based on mathematical statistics. The final result is almost up to the theoretical low limit.4. Comparing with the algorithms of digital filtering in time domain, the design of filter is optimized by genetic adaptive parameter estimation,and new filtering method in time domain based double sampling criterion is proposed. The result verifies effectivity to improve the measurement low limit of the flowmeter.The implement of above-mentioned method needs hardware condition, therefore, a low power double-cores hardware system, composed by Digital Signal Processor (DSP) and microcontroller, is designed.