大Doppler频移条件下基于导频信号的扩频码捕获
Spread-Spectrum Code Acquisition Based on Pilot Symbols in the Presence of Large Doppler Shift
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摘要: 分析了Doppler频移对传统扩频码捕获算法的影响,提出了在发送导频信号期间,利用自适应谱线增强器(ALE)对部分匹配滤波输出进行处理以估计Doppler频移值,经过频偏校正后,采用传统全匹配捕获算法进行扩频码捕获判决的新方法。仿真结果表明,这种方法可以有效地消除大Doppler频移的影响,迅速完成扩频码的捕获。Abstract: The influence of Doppler shifts on traditional acquisition algorithms is analyzed. A new method for spread-spectrum code acquisition of pilot symbols in the presence of large Doppler shifts is proposed, in which the outputs of partial matched filters are delivered to an Adaptive Line Enhancer (ALE) directly and an estimated frequency is produced. After frequency offset compensation, spread-spectrum code acquisition is performed by traditional spread-spectrum code acquisition algorithm. Simulation results show that the new method eliminates the influence of large Doppler shifts effectively, with fast acquisition time.
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