GPS软件接收机导航电文帧同步算法研究

Frame synchronization algorithm of navigation message in GPS software receiver

为了研究恶劣环境下误码率及容错码元个数与帧同步性能的关系,详细阐述了自相关的帧同步方法,并针对帧同步的两个性能指标——漏同步概率和假同步概率与容错码元的关系进行了实验仿真,利用实际采集的GPS中频信号进行了验证。实验结果表明,增加容错码元数可以实现在恶劣环境下提高定位精度的目的。针对不同信噪比的卫星信号,增加一定的容错码元数的帧同步算法能够同步信噪比SNR为-28 dB的微弱信号,相对于常规的-19 dB的信噪比,灵敏度提高了近9 dB。

In order to study the relationship between error rate as well as fault-tolerant symbol number and frame synchronization performance in harsh environments,a frame synchronization algorithm based on autocorrelation function is elaborated. The simulation experiments were performed to validate the relationship between two performance indexes,including missed synchronization probability and false synchronization probability,and the number of fault-tolerant symbol by using the real GPS intermediate-frequency signals. The experimental results show that increasing the number of faulttolerant symbol can improve positioning accuracy in harsh environments. For the satellite signals with respective Signal-to-Noise Ratio（ SNR）,the weak signals whose SNR are- 28 dB can be synchronized by increasing a certain number of fault-tolerant symbol in the frame synchronization algorithm,which means that the sensitivity is improved nearly 9dB relative to the conventional- 19 dB SNR threshold.