Abstract: In order to analyze and estimate the important technical parameter C/N_0, firstly, expatiations of two classical estimation methods VSM (variance summing method) and PRM(power ratio method) are put forward, which are based on the same GPS signal and noise expressions. The reason why the M parameter for PRM should be set that way is presented. A new estimation algorithm MVM(max frequency component divided variance method) is proposed. After that, it analyzes how the navigation data transition impacts on the three algorithms, and enhances the PRM method's immunity from the effects of navigation data transition. Finally, a comparative analysis to these three algorithms in accuracy and stability is provided.

Key words: GPS, C/N_0, navigation bit, VSM, PRM, MVM

摘要： 为了分析和估计载噪比，基于统一的GPS信号和噪声表达式，对两种经典估计算法VSM和PRM的原理进行了推导，并分析了PRM算法的参数M的设定依据。在此基础上，提出了一种新的估计算法MVM。分析了导航位跳变对上述3种算法估计结果的影响，并改进了其中的PRM算法，提高了其抗导航位跳变的能力。最后结合实验结果，在算法准确性和稳定性方面，对以上3种算法做了对比分析。

关键词: GPS, 载噪比, 导航位, VSM, PRM, MVM