A Frequency Correcting Method Combining Bilateral Correction With Weighted Average for Vortex Flow Sensor Signal

The sinusoidal signal outputted by the vortex flow sensor is often superimposed with the white noise, which will affect the accuracy of spectrum correction. When the signal is truncated by rectangular window, a method (hereinafter referred to as RWBWFCR) combining bilateral correction with weighted average on the basis of Fourier coefficients ratio is proposed so as to improve the antinoise performance of the frequency correction. The correction principle of this method is presented. The effects on the frequency correction of changing the initial phase, the frequency deviation, the calculation points of fast Fourier transform, and the signal-to-noise ratio (SNR) are analyzed. The theoretical accuracy of this method when there is stationary Gaussian white noise is deduced and verified. This method has some advantages, such as less computation load, small storage space, high correction precision, strong anti-interference ability, and is easy to be implemented by a microcontroller in real time. RWBWFCR method is applied to the low-power and antivibration type vortex flowmeter with single sensor to improve the reliability of the digital signal processing method based on the frequency correction.