针对突发直扩信号跟踪的算法迭代改进和鉴相器优选

Tracking Algorithm Improvement using Iterative Kalman Filter and Discriminator Optimal Selection for Burst DSSS Signals

  • 摘要: 北斗卫星无线电测定业务(RDSS)入站信号采用突发直扩体制,为保证基于短时突发信号伪码同步的伪距测量性能,提出了一种新的基于迭代的卡尔曼跟踪算法。迭代跟踪算法首先利用捕获或粗跟提供的码相位和载波相位频率初值完成一次前向跟踪,然后采用后向估计算法回推得到一组精度更高的码相位和载波相位频率初值,然后基于该组初值再次进行前向跟踪和后向估计,数次的前向和后向迭代有效的减小了捕获或粗跟提供的码相位初值和载波相位频率初值误差对载波和码跟踪精度的影响。前向跟踪或后向估计时,根据本次迭代起始时刻码和载波相位初值误差大小优选本次迭代码鉴相方法,码鉴相方法优选进一步提高了最终的码测量精度,为便于码鉴相方法优选,推导了一种针对频带受限信号的似相干点积功率码鉴相器性能估计方法。仿真结果表明,本文提出的算法性能优于传统算法。

     

    Abstract: To enhance the pseudo-range measure performance based on code synchronization of short burst DSSS signals, such as the RDSS inbound signal of Compass, a new kalman tracking algorithm based on iteration is proposed. After a code and carrier forward tracking based on initial values provided by acquisition or coarse tracking, a back estimation is followed to get more precise values of initial parameters of the received signal at the beginning point. By utilizing these precise initial values, forward tracking based on the same received signal is carried out again. By doing forward tracking and backward estimation iteratively, more and more precise tracking results are achieved. At the beginning of each forward tracking or backward estimation, an optimization of code discriminator is carried out considering the precise of initial carrier and code phase, which improves the final precision of code synchronization any more. For the convenience of optimization, a performance estimation algorithm of dot product power code discriminator for banded signal is proposed. Compared with several traditional tracking algorithms, simulation results and practical adoption during RDSS signal tracking of Compass show the excellence of our proposed algorithm.

     

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