科氏流量计的时变信号处理方法

针对实际应用中科氏流量计流量缓变的特性,首先建立频率、幅值和相位均按照随机游动模型变化的改进时变信号模型,其次采用一种跟踪信号频率变化能力更好的陷波算法对信号进行滤波,以求其频率；并采用自适应谱线增强器从含有噪声的信号中提取出基频信号；然后通过短窗截取,采用修正的滑动DTFT递推算法实时计算两路信号之间的相位差和时间差,求得质量流量.仿真及实测结果表明,研究方法不仅可以跟踪变化的频率和相位,而且在测量小相位时具有较高的精度,整套算法计算量小,可用于科氏流量计的实时信号处理.

A time-varying signal processing method for Coriolis mass flowmeter

The mass flowrate of Coriolis mass flowmeter in practical application has slow changes with time. To solve the problem, an improved time-varying signal model whose frequency, amplitude and phase are time-varying based on the random walk model is established firstly. A new algorithm of adaptive notch filter with the capability of tracking frequency variation is applied to filter the sensor output signal of Coriolis mass flowmeter and its frequency is calculated next. An adaptive line enhancer based on the mentioned notch filter extracts fundamental frequency signal from noisy data. Then, by short window intercepting, the revised sliding DTFT recursive algorithm is introduced to calculate the real-time phase difference between two enhanced signals. With the frequency and phase difference obtained, the time interval between the two signals is calculated and then the mass flowrate is derived. The simulations and field test results show that the proposed method can not only track the change of frequency and phase, but also ensure the calculation accuracy when measuring small phase difference. The computational load of the algorithm is simple so that it can be applied to real-time signal processing for Coriolis mass flowmeter.