用FFT测量周期信号相角差及其误差分析

The Measurement of Phase Angle Difference between Periodic Signals Using FFT and Its Error Analysis

分析了用ＦＦＴ测量周期信号相角时误差的来源，对非整周期采样造成的泄漏误差进行了估计；当采样总时间足够长时，相角测量值与实际值基本上相差一个与非整周期数成比例的常数；在测量两信号的相角差时，主要误差恰好抵消，得到了很高的测量精度．

This paper analyses the error of phase angle measurement of periodic signal.The leakage error caused by non-integral periodic sampling is estimated. It is shown that when the total sampling time is long enough, the leakage error will be almost in proportion to the fractional period of sampling. thus, the measurement of phase angle difference between two periodic signals will be rather accurate because the main error will cancel out each other.