摘要
空间激光通信中的常用调制方式是脉冲位置调制 (PPM) ,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 ,因而成为空间激光通信中的首选信号探测器件。针对空间激光通信的脉冲位置调制信道 ,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 ,根据小波变换具有提取信号局部特征的能力 ,提出了一种基于小波变换的雪崩光电二极管信号检测方法。采用四种不同的阈值选择算法选取小波系数以恢复信号 ,并进行了初步的仿真实验和分析。结果表明 ,自适应阈值选择算法取得的信号恢复结果最佳 ,可有效减弱强背景噪声的影响 ,提高雪崩光电二极管信号检测系统的性能。
Pulse position modulation (PPM) is the most often used modulation technique in space laser communications. As avalanche photodiode detector (APD) has high gain, high sensitivity and fast response, it is a likely candidate to detect laser signals for providing space laser communications needs. This paper discusses the characteristics and sorts of noises in the APD signal detecting subsystem, as the PPM channel is considered in the space laser communication system. Based on the ability of achieving topical characteristics of signals by the wavelet transform, a method of APD signal detecting based on the wavelet analysis is proposed. Four different threshold limit selecting methods are applied to choose the wavelet coefficient for signal recovering. A primary simulation experiment and some analyses are also done. The results show that the adaptive threshold values selecting algorithm is the best one. It can mitigate the effect of the intensive background noise to improve the performance of the APD signal detecting system.
出处
《中国激光》
EI
CAS
CSCD
北大核心
2004年第4期465-468,共4页
Chinese Journal of Lasers
关键词
信号检测
空间激光通信
脉冲位置调制信道
雪崩光电二极管探测器
探测噪声
小波变换
signal detect
space laser communication
pulse position modulation channel
avalanche photodiode detector
detection noise
wavelet transform
