In order to study the relationship between error rate as well as fault-tolerant symbol num-ber and frame synchronization performance in harsh environments, a frame synchronization algorithm based on autocorrelation function is elaborated. The simulation experiments were performed to vali-date 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 fault-tolerant 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 syn-chronized by increasing a certain number of fault-tolerant symbol in the frame synchronization algo-rithm, which means that the sensitivity is improved nearly 9dB relative to the conventional-19 dB SNR threshold.%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。
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