多普勒频率变化率快速最大似然估计辅助的高动态载波跟踪环路  

Carrier Tracking Loop in High Dynamic Environment Aided by Fast Maximum Likelihood Estimation of Doppler Frequency Rate-of-change

作　　者：郇浩[1] 陶选如 陶然[1] 程小康[1] 董朝[1] 李鹏飞[1] 

机构地区：[1]北京理工大学信息与电子学院,北京100081

出　　处：《电子与信息学报》2014年第3期577-582,共6页Journal of Electronics & Information Technology

基　　金：教育部博士点基金(20121101130001);CAST重点基金(201215);北京市自然科学基金(4112051)资助课题

摘　　要：高动态环境下接收信号含有较大的多普勒频率及其变化率,传统载波跟踪方法难以在高动态应力和跟踪精度两方面取得较好折中,针对这一问题该文提出一种多普勒频率变化率快速最大似然估计方法,并利用估计值辅助载波跟踪环路。首先指出了多普勒频率及其变化率的最大似然估计可等效采用分数阶傅里叶变换(FrFT)来实现;其次,针对频率及其变化率2维搜索运算量大的问题,提出一种瞬时自相关与分段离散傅里叶变换(DFT)求相位差相结合的频率变化率估计方法,根据粗估值可大大缩小搜索范围;最后,利用估计值辅助载波跟踪环路,降低动态应力,提高跟踪精度。理论分析与计算机仿真表明,在典型高动态参数条件下,输入信噪比为-30 dB时,搜索运算量降为原来的5.25%,输出频率的均方根误差仅为8.46 Hz/s,和传统载波跟踪方法相比,灵敏度提高3 dB以上。To reach a compromise between efficient dynamic performance and high tracking accuracy of carrier tracking loop in high-dynamic circumstance which results in large Doppler frequency and Doppler frequency rate-of-change, a fast maximum likelihood estimation method of Doppler frequency rate-of-change is proposed in this paper, and the estimation value is utilized to aid the carrier tracking loop. First, it is pointed out that the maximum likelihood estimation method of Doppler frequency and Doppler frequency rate-of-change is equivalent to the Fractional Fourier Fransform （FrFT）. Second, the estimation method of Doppler frequency rate-of-change, which combines the instant self-correlation and the segmental Discrete Fourier Transform （DFT） is proposed to solve the large two-dimensional search calculation amount of the Doppler frequency and Doppler frequency rate-of-change, and the received coarse estimation value is applied to narrow down the search range. Finally, the estimation value is used in the carrier tracking loop to reduce the dynamic stress and improve the tracking accuracy. Theoretical analysis and computer simulation show that the search calculation amount falls to 5.25 percent of the original amount with Signal to Noise Ratio （SNR）-30 dB, and the Root Mean Sguare Error（RMSE） of frequency tracked is only 8.46 Hz/s, compared with the traditional carrier tracking method the tracking sensitivity can be improved more than 3 dB.

关 键 词：载波跟踪 高动态 最大似然估计 瞬时自相关 离散傅里叶变换 

分 类 号：TN911.23[电子电信—通信与信息系统]