In order to reduce the average estimation time of the Global Navigation Satellite System (GNSS) receiver in performing bit synchronization, a novel adaptive bit synchronization algorithm was proposed. The traditional maximum likelihood bit synchronization algorithm was analyzed, and the relationship among the signal intensity, the maximum bit energy and the number of incoherent accumulation was found. On this basis, the number of non-coherent accumulation times of the threshold constraint was set by using the maximum bit energy, so that the bit synchronization algorithm could adjust the non-coherent accumulation times for different signal intensities. Simulation analysis shows that the correct synchronization probability of the proposed adaptive algorithm is only 5% lower than that of traditional fixed non-coherent accumulative bit synchronization algorithm when the preset threshold is 1.5×108. However, its average estimated time is reduced by 85%, which makes the first fixed time of the receiver be largely reduced.%为了降低全球卫星导航系统(GNSS)接收机做比特同步的平均估计时间,提出一种自适应比特同步的新颖算法.分析了传统的最大似然比特同步算法,找到了信号强度、比特能量最大值和非相干累加次数三者之间的关系.在此基础上,利用比特能量最大值来设置门限约束非相干累加次数,使得比特同步算法可以针对不同信号强度来自适应地调整非相干累加次数.仿真分析表明,当预设的门限值为1.5×108时,与传统的固定非相干累加比特同步算法相比,所提出的自适应算法的正确同步概率性能只略微下降了5%,但平均估计时间缩短了85%,使得接收机的首次定位时间大幅度减少.
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