激光大气闪烁的小波频谱分析

Wavelet Spectrum Analysis of Laser Scintillation in a Turbulent Atmosphere

激光对数光强起伏的快速傅里叶变换功率谱的无标度区间的标度指数在许多情况下很不稳定， 并且超出了理论界限， 因而本文引入了离散小波变换（ＤＷＴ）频谱分析。通过对１／ｆ 信号的快速傅里叶变换频谱和离散小波变换频谱的对比分析， 验证了离散小波变换频谱分析的优越性。激光大气闪烁的离散小波变换频谱的无标度区间的标度指数在一天内（除日出后和日落前两段时间外）的变化比较稳定， 并且不超出理论界限。这些结果表明，

Since scaling exponents fitted from many fast Fourier transformation (FFT) power spectra of the log intensity of laser beam in the turbulent atmosphere go beyond the theoretical bound, the discrete wavelet transformation (DWT) power spectrum was introduced. The superiority of DWT over FFT is verified through comparison of the scaling exponents fitted from the FFT and DWT power spectra of 1/f noises. The scaling exponents in the scaling region of the DWT power spectrum of laser scintillation vary smoothly in a whole day (except sunrise and sunset time) and lie in the bound. It is suggested that DWT instead of FFT should be used in the spectrum analysis of laser scintillation.