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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 Unbi-ased 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.
According to the characteristics of standard digital terrestrial transmission frame structure in China, a large-scale frequency deviation capture method is proposed. This algorithm utilizes PN sequence after the addition of Pseudo Noise (PN) sequence, The local PN sequence differential cross-correlation get the desired frequency offset value, and then use the BLUE (Best Linear Unbi-ased Estimator) method, without loss of frequency offset accuracy under the premise of expanding the frequency offset estimation range of the algorithm before the frame synchronization The fast acquisition of a large range of frequency offsets provides the necessary conditions for the reliable implementation of frame synchronization and frequency offset tracking.The simulation results show that the proposed algorithm can quickly lock the frequency offset and frequency in one frame time compared with the traditional differential cross-correlation algorithm The partial estimation range has been enlarged by H times and the frequency offset accuracy has not changed.