一种基于软相关的GNSS比特同步方法  

A Soft-related GNSS Bit Synchronization Method

作　　者：张剑 邵晨光 李满庆 

机构地区：[1]中国兵器工业导航与控制技术研究所,北京100089

出　　处：《全球定位系统》2017年第5期63-67,共5页Gnss World of China

摘　　要：GNSS接收机中因为比特同步错误而导致的导航电文提取失败和伪距计算错误等问题非常普遍。目前的比特同步算法主要是直方图法。其中,基于硬判决的直方图法应用较为广泛,主要是因为其实现方便,但在低载噪比下同步成功率太低,无法满足工程需求。因此,需要对低信噪比下的bit同步算法进行研究。本方案提出了直方图法与软相关结合的bit同步算法。首先,模拟产生在不同载噪比下的GNSS信号数据,它有20个比特边界。然后,采用两种算法进行比特同步。重复仿真多次,每次仿真采用随机的比特边界,得到每种算法在不同载噪比下的正确比特同步概率。分析仿真结果发现,比特同步的时间越长,各算法的正确概率越大。在低载噪比下,软相关方法远高于传统的直方图法。最后基于altera arriaV芯片完成了软相关的比特同步方案工程实现。In the GNSS receiver,it is very common to extract the navigation message caused by bit synchronization errors,such as the failure of the navigation message and the error of the pseudo range.The current bit synchronization algorithm is mainly based on the histogram method.Among them,the histogram method based on hard decision is widely used,mainly because of its convenient implementation,but its low noise ratio is too low,can not meet the needs of the project.Therefore,it is necessary to study the bit synchronization algorithm under low SNR,this scheme adopts the bit synchronization algorithm with the combination of histogram method and software.First,the GNSS signal data is generated at different carrier to noise ratio,and it has 20 bit boundaries.Then,two algorithms are used to carry out bit synchronization.Repeated simulation times,each time the simulation using random bit boundary,get the correct bit synchronization probability of each algorithm in different carrier to noise ratio.The simulation results show that the longer the bit synchronization time is,the greater the probability of the algorithm is.In the low carrier to noise ratio,the soft correlation method is much higher than the traditional histogram method.Then the soft correlation method was implement in altera arriaV.

关 键 词：比特同步 软相关 低信噪比 正确概率 

分 类 号：P228.4[天文地球—大地测量学与测量工程]