摘要
本文提出了一种适用于低轨卫星扩频通信系统的多普勒频移快捕方法 .该方法基于数字匹配滤波器及自动频率控制环路 ,利用数字匹配滤波器的PN码快捕特性及其输出主相关峰值对频偏的敏感性 ,缩短多普勒频移的捕获时间 .论文首先推导了多普勒频移的平均捕获时间表达式 ,然后根据数值分析结果得到了准最佳捕获判决策略 。
A rapid acquisition scheme of Doppler shift is proposed for a LEO satellite spread-spectrum communications system. Based on the use of digital matched filter (DMF)and automatic frequency control (AFG)loop, two characteristics of the DMF are exploited to reduce the mean acquisition time (MAT) of Doppler shift, namely, the rapid acquisition property of PN code and a high sensitivity of maximum correlation value to frequency offset. An expression of the MAT is derived, and a suboptimal decision of acquisition is given out from numerical results. Finally, the performance of the proposed acquisition scheme is compared with the traditional serial scheme, showing a significant improvement achieved.
出处
《电子学报》
EI
CAS
CSCD
北大核心
2003年第7期1052-1056,共5页
Acta Electronica Sinica
关键词
卫星通信
数字匹配滤波器
自动频率控制环路
多普勒频移捕获
Calculations
Doppler effect
Electric frequency control
Optimization
Probability
Sensitivity analysis
Spread spectrum communication
