移相相关法计算相位差的研究

为了提高相位式测距仪的测量精度，采用移相相关方法来估计两同频正弦信号的相位差。首先将每路信号移相2π后和原信号做相关来计算自相关，以减少噪声的影响；其次用少许数据初步估算相位差，并将一路信号移相，使两路信号的相位差移到π/2（或3π/2）附近；然后用较多的采样数据计算两路信号的相位差，将结果再减去移相量得到最终的相位差。同时分析了频率误差对相位差计算精度的影响，进行了理论分析和仿真实验验证。结果表明，该方法计算的误差大大减小。这对提高测距仪的测量精度是有帮助的。

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.