The question of multi-band and high dynamic signal is studied,and the difficulty of frequency acquisi-tion from multi-band is analyzed. Aiming at low data rate and large frequency offset,the influence of decimation times on frequency acquisition is analyzed. The acquisition scheme of changing decimation times and then esti-mating frequency offset according to the maximum power search method is proposed. Simulation result shows that,compared with the traditional method,this scheme is better under low SNR,and can adapt to UHF and S band,and at 9.6 kb/s data rate,the precision is 300 Hz in UHF band,600 Hz in S band.% 研究了多频段高动态信号载波频偏问题,分析了多频段给频偏捕获带来的困难,针对低数据率、大载波频偏的情况,讨论了抽取倍数对捕获范围和精度的影响,并提出对于不同频段,通过改变相应的抽取倍数来满足不同的频偏和精度,再进行最大功率搜索法估计频偏的捕获方案.仿真结果表明,与传统方法进行比较,该方案在低信噪比下条件下估计性能更好,能够适应UHF和S频段,在数据率9.6 kb/s的条件下,估计精度在UHF频段下为300 Hz,在S频段下为600 Hz.
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