摘要
在近地轨道 (LEO)航天器通信中 ,航天器的高动态使扩频信号存在多达几十kHz甚至上百kHz的多普勒频移。对于存在如此之大的多普勒频移的扩频信号 ,采用传统的捕获方法 ,整个捕获过程非常困难 ,捕获时间很长。文中提出一种应用于存在较大多普勒频移的环境中、利用FFT谱分析进行伪码捕获的方法 ,并对其捕获性能进行分析。结果表明 ,与传统相关检测方法相比 ,采用基于FFT的捕获方法能减少捕获时间 。
This paper describes a technique for fast code acquisition of direct sequence spread spectrum signals in the high dynamic environments in which large Doppler shifts existed. In this paper we use PMF-FFT structure to search the code phase and estimate the Doppler shifts simultaneously.We also present a structure to improve the precision of Doppler estimation.It is shown that the FFTbased method can significantly accelerate the acquisition process and reduce the cost of FPGA resources in the presence of large Doppler shifts.
出处
《遥测遥控》
2004年第6期19-24,共6页
Journal of Telemetry,Tracking and Command
关键词
FFT
伪码捕获
多普勒频移
扩频
FFT Code acquisition Doppler shifts Spread spectrum
