大气湍流对APD直接检测接收机抗噪声性能影响

Influences of Atmosphere Turbulence to Noise Rejection for Direct Detection Using Avalanche Photodiode

针对以往分析湍流信道对系统抗噪声性能影响的不足，给出了一种基于APD直接检测接收机的湍流噪声的处理方法。在APD直接检测接收机模型的基础上，推导了其信噪比和曼彻斯特编码系统的差错概率，并详细分析了湍流对接收机的抗噪声性能影响。结果表明，增大接收天线孔径可以减弱湍流的影响，但在天线孔径较小时，增加发射功率并不能有效地提高系统的可靠性。对于同一孔径的天线来讲，较大闪烁指数下的孔径平滑效应比较小闪烁指数下的平滑效应明显。所给方法既能分析点孔接收，又能分析孔径平滑效应，可为大气信道下光通信链路的差错性能估算及功率预算等方面提供有力帮助。

A method to deal with noise caused by atmosphere turbulence was proposed for direct detection （DD） using avalanche photodiode （APD） in respect that limitation of some documents appeared. After giving the mode of DD-receiver, its signal-to-noise ratio （SNR） and code error rate of Manchester system were derived and analyzed influences of turbulence to DD-receiver using APD. Numerical results showed that system reliability only enhanced a little with increase of transmit power under small antenna dimension. For an antenna, its smoothing effect to large scintillation index is better than to small scintillation index. The method in this paper could help to estimate the error performance and power requirement for optical communication link through atmosphere turbulence.