基于低阶EKF联合的相干与非相干积分组合跟踪算法

Tracking algorithm based on low order EKF combination of coherent and incoherent integration

针对弱信号环境B1C信号难以跟踪以及积分时间难以延长的问题,设计了一种基于低阶扩展卡尔曼滤波(EKF)联合的相干与非相干积分组合跟踪算法。首先,分析了B1C信号结构,建立了数据和导频通道相关器联合跟踪模型;其次,根据B1C在弱信号环境下的变化特点,设计了相干与非相干积分组合跟踪算法;最后,利用模拟信号发生器生成-144 dBm的B1C弱信号,进行了仿真实验验证。实验结果表明,低阶EKF联合跟踪算法采用20 ms长相干积分,载波与伪码跟踪误差分别为0.014 rad与0.027 chip。采用相干积分与非相干积分组合积分后,载波与伪码跟踪误差均提高14%以上,且对更长积分时间的适应性明显提高,能够改善B1C弱信号的跟踪能力。

Aiming at the problems that B1C signal in weak signal environment is difficult to track and the integration time is difficult to extend,a tracking algorithm based on low-order extend Kalman filter(EKF)combination of coherent and incoherent integration is designed.Firstly,the B1C signal structure is analyzed,and the joint tracking model of data and pilot correlator is established.Secondly,according to the characteristics of B1C in weak signal environment,the coherent and incoherent integrated tracking algorithm is designed.Finally,an analog signal generator is used to generate B1C weak signals of-144 dBm,which are verified by simulation experiments.The experimental results show that,using coherent integration,the low-order EKF joint tracking algorithm reaches its minimum tracking errors at 20 ms integration period.The pseudo-code tracking error is 0.027 chip while the carrier tracking error is 0.014 rad.The proposed combination of coherent and non-coherent integration is able to reduce both carrier and code tracking error when integration period above 20 ms.The improvements are more than 14%and more capable of tracking weak B1C signals.