大Doppler頻移條件下基于導(dǎo)頻信號(hào)的擴(kuò)頻碼捕獲
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頻移對(duì)傳統(tǒng)擴(kuò)頻碼捕獲算法的影響,提出了在發(fā)送導(dǎo)頻信號(hào)期間,利用自適應(yīng)譜線增強(qiáng)器(ALE)對(duì)部分匹配濾波輸出進(jìn)行處理以估計(jì)Doppler頻移值,經(jīng)過頻偏校正后,采用傳統(tǒng)全匹配捕獲算法進(jìn)行擴(kuò)頻碼捕獲判決的新方法。仿真結(jié)果表明,這種方法可以有效地消除大Doppler頻移的影響,迅速完成擴(kuò)頻碼的捕獲。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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