基于自适应提升小波的APD探测信号消噪

Denoising of APD Signal Detecting Based on Adaptive Lifting Wavelet

雪崩光电二极管(APD)具有高增益、高灵敏度和响应速度快的特点,因而成为空间光通信中的首选信号探测器件。针对空间光通信的脉冲位置调制(PPM)信道,分析了空间光通信系统中雪崩光电二极管探测噪声的特点和类别,在讨论了第二代小波变换基本原理及其特点的基础上,将自适应性引入提升方案中,用先更新后预测的改进提升算法解决自适应性引起的非线性问题,并在阈值处理过程中引入了软硬阈值折衷法来恢复信号。实验仿真结果表明,采用该算法实现的雪崩光电二极管信号去噪,不仅较好地剔除信号中的噪声,而且保留了原始信号中的有效成分,是一种可行的方法。

Because of its high gain, high sensitivity and fast response, Avalanche Photodiode Detector（APD）is considered to be a best device for laser signals detection in space optical communication. As the Pulse Position Modulation（PPM） channel is considered, the characteristics and sorts of noises in the APD signal detecting subsystem are discussed. According to the theory and characteristics of the second generation wavelet transform, the improved algorithm is proposed by using adaptive algorithm. The problem of nonlinear caused by adaptive algorithm is solved by using updating-before-predicating lifting scheme, and the compromise algorithm between software-threshold and hard-threshold is used in the threshold processing. The simulated results show that the improved lifting scheme used in APD detecter not only filters the noise, but also retains the effective composition in the original signal and this algorithm of signal denoising is a feasible method.