【作者】 解孟其； 柯熙政；

【Author】 Xie Mengqi;Ke Xizheng;School of Automation and Information engineering,Xi’an University of technology;

【机构】 西安理工大学自动化与信息工程学院；

【摘要】 大气信道对光强调制直接检测的无线光通信系统存在乘性噪声的影响。本文以无线光通信中的副载波调制技术为背景,研究了光强调制QPSK信号的循环自相关和循环谱密度函数,并与实际测得的信号的循环谱对比分析。结果表明,加性高斯白噪对循环谱的影响集中在循环频率为零处,而大气信道引入的乘性噪声在循环谱上的特定频点分布,因此大气信道引入的乘性噪声与加性高斯白噪有本质的区别:该乘性噪声具有循环稳定性,并且是单频点的有色噪声。更多还原

【Abstract】 Atmosphere channel influence Free Space Optical(FSO) commumcation systems of Intensity Modulation and Direct Detection(IM/DD) by multiplicative noise.Based on sub-carrier modulation,cyclic auto-correlation and cyclic spectral density of QPSK signal are researched in this essay.Then the cyclic spectral density of a set of experimental measured data is calculated.The results show that the multiplicative noise induced by atmosphere channel is far different from Additive White Gaussian Noise(AWGN).The multiplicative noise in FSO-QPSK signal is cyclostationary.And it is colored noise with single specific frequency point.更多还原