多径环境下TDDM-BOC信号伪码周期估计

针对低信噪比下存在多径效应的时分数据调制二进制偏移载波( TDDM-BOC )调制信号的伪码周期估计难题，提出了一种基于二次谱的TDDM-BOC信号伪码周期估计算法。该算法首先推导出多径环境下TDDM-BOC信号模型，然后求出多径TDDM-BOC信号的功率谱，再求其二次谱，最后通过检测二次谱的尖峰脉冲间的间距得到多径环境下TDDM-BOC信号的伪码周期。实验过程中采用累加平均的方法可以达到降噪和精确估计的目的。仿真结果表明：该算法能够在多径环境下对TDDM-BOC信号伪码周期进行有效估计，且估计性能与多径环境有密切关系，这为今后我国“北斗冶导航接收设备的开发提供了一定的理论参考。

Period estimation of PN sequence for TDDM-BOC signal in multipath environment

For the problem of estimating pseudo-code period of Time Division Data Modulation-Binary Offset Carrier(TDDM-BOC)signal with multipath effect under low signal-to-noise ratio(SNR),an algorithm based on quadratic spectrum is proposed to estimate the pseudo-code period of TDDM-BOC signal. Firstly,the TDDM-BOC signal model in multipath environment is derived. Then the power spectrum of the multipath TDDM-BOC signal is found,its secondary spectrum can be obtained by using Fourier transform of the power spectrum. Finally,the pseudo-code period of TDDM-BOC signal in multipath environment can be got by detecting spacing between peak pulses. The method of accumulative average is adopted to achieve the purpose of noise reduction and accurate estimation. Simulation results show that the pseudo-code period of TDDM-BOC signal in multipath environment is effectively estimated by using the algorithm and its performance closely relates with the multipath environment. It has a certain reference value for Beidou navigation receiver design.