基于FRFT的多普勒频率跟踪算法

高动态环境下卫星通信终端面临高动态和低信噪比问题,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,在信号设计中考虑插入分散导频用于跟踪载波,可在低信噪比下实现高机动用户多普勒频移捕获及多普勒频率变化率的跟踪。给出了一种基于FRFT的频率变化率估计方法,利用估计值辅助载波跟踪环路。理论分析与计算机仿真表明,在典型高动态参数条件下,基于分散导频的多普勒频率跟踪算法和传统载波跟踪方法相比,灵敏度提高2 dB以上,Es/N0工作点可低至0 dB以下,跟踪范围可达符号速率的2倍,频率跟踪的均方根误差小于符号速率的1%,性能损失小于0.1 dB。

Doppler Frequency Track Algorithm Based on FRFT

In high dynamic environment,the satellite terminal faced high dynamic and low SNR problems,traditional carrier track method cannot meet both high dynamic and track precision.Disperse pilot code can be used to track carrier phase in high dynamic and low SNR.A frequency and frequency change rate trace method based on FRFT is given.Theoretical analysis and simulation show that,in the typical High dynamic environment,carrier track method based on disperse pilot code can improve the sensitivity more than 2 dB,Es/N0 can be lowed to under 0 dB,trace bound can be 2 times of Fs,carrier frequency track precision can be 1%,and the performance loss can be lower than 0.1 dB.