基于谱线平移的低信噪比高动态信号多普勒频偏捕获算法

Doppler Frequency Offset Acquisition Algorithm Based on Spectrum Line Shift for High Dynamic Signal with Low SNR

针对低信噪比高动态信号的载波频偏捕获提出了一种新的算法即谱线平移算法.首先,介绍了现有的大载波频偏捕获技术,分析了其不能适应高动态信号捕获的原因;其次,分析了载波频偏及其变化率对载波频偏捕获的影响,主要考虑多普勒频移变化率对信号捕获的影响,它将严重限制低信噪比情况下对载波频偏估计时非相干累加的次数,在此基础上,提出并研究了适应低信噪比高动态信号大载波频偏捕获的谱线平移算法,并对算法进行了性能仿真,表明其具有2 ～3dB的改善增益,与最大似然算法相比具有绝对优势.

A new algorithm is provided for carrier frequency offset acquisition for high dynamic signal with low SNR, and it is spectrum line shift algorithm. Firstly, current large carrier frequency offset acquisition technology is introduced, and the reason why this technology cant adapt to high dynamic signal acquisition is analyzed. Secondly, carrier frequency offset acquisition affected by cartier frequency offset and its rate of change is analyzed. It＇s mainly considered that Doppler frequency shift change rate affects signal＇s acquisition. Doppler frequency shift change rate seriously reduces non -coherent accumulation number during carrier frequency offset estimation at low SNR. On this base, spectrum line shift algorithm is provided and researched, and it can adapt to large cartier frequency offset acquisition for high dynamic signal with low SNR. It＇s shown that the algorithm has improvement of gain of 2 -3dB, and compared with ML, the algorithm has absolute advantage by MATLAB simulation.