Study on phase difference algorithm based on phase-shift correlation analysis

In order to improve the accuracy of a phase-shift range finder, a phase-difference algorithm based on phase-shift correlation analysis was proposed to estimate the phase-difference between two sinusoidal signals with same frequency. For reducing the influence of noise, the autocorrelation between the original and 2π shifted signal was calculated firstly. Secondly, the phase difference was estimated approximately with a few sampled data and the initial phase of one signal was shifted by Δθ to make the phase difference between two signals to be near π/2(or 3π/2). Then, the phase-difference was calculated with whole set of data by correlation method and the final phase difference was obtained by subtracting Δθ. The influence of frequency error was analyzed. Theoretical analysis and simulation shows that the error of this method is greatly reduced. The proposed method can improve the accuracy of a range finder.