Abstract:

The influence of negative frequency component on the measurement of phase difference is analyzed when the all-phase discrete Fourier transform (apDFT) algorithm is utilized. A delay-compensation method base on iteration is put forward to reduce the systematic error caused by the negative frequency component, and its performance in reducing the systematic error is discussed when the window function is applied. When the apDFT algorithm is used to measure phase difference, the negative frequency component can cause a systematic error of several degrees. The delay-compensation method based on iteration combined with the apDFT algorithm can reduce the maximal systematic error to 0.01° level in the whole bandwidth when the number of points for discrete Fourier transform (DFT) is 1 024. Besides, the larger the number of points for DFT is, the better of the performance will be. When the original data is windowed by a cosine function, the performances of the delay-compensation method based on iteration are improved in the reduction of systematic error and the tolerance of noise.