一种新型的用于深空高动态微弱信号载波跟踪环

Carrier loop for high dynamic and weak signal in deep space

分析了深空通信中高动态微弱信号载波跟踪方法,提出并分析了载波跟踪中状态方程非线性与量测方程的非线性取舍问题,分析了滤波过程中影响高动态与低信噪比的决定因素,给出了两个推论,提出了强跟踪算法的必要性。并以此选择了以传统卡尔曼滤波(KF)为基础,以锁相环(FLL)、无迹卡尔曼滤波(UKF)为辅助使用两种工作模式来应对不同环境。针对组合跟踪环路状态转换过渡易出现的频率阶跃问题,给出新型环路的工作模式及切换门限的数学表达式,在环路中添加计算判别器,实时控制环路输出的同时不浪费计算力地剔除了野值,提高了环路稳定性。仿真表明,该新型环路算法与现有的算法相比有很好的低信噪高动态适应能力,消除了切换峰值,剔除了野值。

High dynamic and weak signal carrier tracking methods in deep space communication was analyzed.The nonlinear selection problem of state equation and measurement equation in carrier tracking was proposed.The determinants in high dynamic weak signal tracking were discussed and two inferences were given.Based on Kalman filter,phase-locked loop(FLL)and unscented Kalman filter(UKF)were used to assist in different environments.Aiming at the frequency step problem in the combination tracking loop state transition,the mathematical expression of the working mode and switching threshold of the novel loop were presented.Calculation discriminator in the loop controls the loop output and at the same time eliminates the wild value.The simulation shows that the loop algorithm has good low signal-to-noise and high-dynamic adaptability compared with the existing algorithms.