Rapid large frequency offset estimation for DTMB system
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摘要: 根据中国数字电视地面传输标准帧结构特点,提出了一种大范围频率偏差捕获方法.该算法利用PN(Pseudo Noise)序列移位相加后仍为PN序列这一特征,通过帧头PN序列与本地PN序列的差分互相关得到待求的频偏值,然后利用BLUE(Best Linear Unbiased Estimator)方法,在不损失频偏精度的前提下扩大频偏估计范围.该算法能在帧同步前快速捕获大范围频偏,为可靠实现帧同步以及频偏跟踪过程提供了必要条件.仿真结果表明,相对于传统的差分互相关算法,该算法能在一个帧头时间内快速锁定频偏,频偏估计范围扩大了H倍且频偏精度不变.Abstract: A frequency synchronization algorithm for digital terreslrial television multimedia broadcasting (DTMB) system with a large frequency offset was developed. The estimated frequency offset was obtained by differential correlation between received pseudo noise (PN) sequence and local PN sequence based on the m sequence cyclic shift-and-add property. Best linear unbiased estimator was used to enlarge the estimation range and maintain the estimation accuracy. This scheme could finish carrier frequency acquisition even with large frequency offset in a short time, and provide the necessary conditions for frequency offset tracking. Simulation results under AWGN and multipath channels show that the proposed scheme enlarges the frequency estimation range by H times with the same accuracy compared with the traditional differential correlation algorithm used for frequency synchronization in DTMB system.
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