基于相干小波变换的信号相位差估计

Phase delay estimator based on coherency wavelet transform

精确地估计两列信号间的传输延迟在工程上有着重要的意义。傅里叶变换方法很难区分或识别信号的瞬时变化,而小波变换方法是一种时间窗和频率窗都可改变的时频局部化的分析方法,在非平稳信号的分析方面具有明显的优势。给出应用Morlet小波变换的相干性实现两信号相位差估计的算法,在不同信噪比条件下,对算法的估计性能进行了仿真研究。仿真研究结果表明,在低信噪比的条件下,基于小波变换的相位差估计方法可以实现信号相位差的精确估计。通过与基于离散时间傅里叶变换方法的比较,验证了小波变换方法在估计信号相位差方面的优越性。该方法还可用于对非平稳信号相位差的估计。

Accurate estimation of phase delay between two signals is very important. The Fourier transform method is suitable for deterministic signals. However, it is hard to distinguish or identify signals＇ transient changes. The wavelet method allows to capture the time and frequency varying features of signals. It also has the obvious advantages in analyzing nonstationary signals. The coherency wavelet transform using Morlet wavelet is proposed to estimate the phase delay of two signals. The estimation performances are studied at different conditions. The simulation results show that the wavelet-based method can accurately estimate the phase delay at low SNR. In comparison with DTFT, the advantage of wavelet-based method is validated. This method can also be used to estimate the phase delay between two non-stationary signals.