The fast and high-precision positioning with multiple Global Navigation Satellite Systems (multi-GNSS) has been challenging for decades. Although the single-frequency single system (SF-SS), satellite selection for multi-GNSS, and multi-GNSS-based partial ambiguity resolution (PAR) can achieve rapid positioning, the varying theoretical bases of them result in different fixed reliability of ambiguities. Hence, we provide the theory analyzing the ambiguity resolution capabilities of the named systems. By adding satellite observations, the equations giving the variance–covariance matrix variation of the original float parameters are derived. Then, the relationship between the ambiguity dilution of precision (ADOP) values of the original ambiguity vector (OAV) before and after adding observations is obtained. This is followed by the analyses of the changing trends in the OAV’s probability density function, integer least-squares pull-in region, and the R-ratio test-based integer aperture pull-in region. In terms of precision, ADOP, and R-ratio test-based fixed reliability of ambiguities, the analyses indicate that the multi-GNSS can improve the partial ambiguity estimation and validation. Besides, compared to satellite selection and SF-SS, the PAR is optimal. The BeiDou Navigation Satellite System (BDS) and the Global Positioning System (GPS)-based single-epoch positioning experiments showed that both BDS B1 and B1-based PAR outperform GPS L1 and L1-based PAR in terms of ADOP and R-ratio test-based fixed reliability. The ADOP of the former is smaller than 0.14, and both the R-ratio test-based acceptance and success rates are up to 99.64%. Finally, the false alarm, failure, and detection rates are reduced to 0.34%, 0.0%, and 0.02%, respectively.

数十年来，使用多个全球导航卫星系统（multi-GNSS）进行快速，高精度的定位一直是一项挑战。尽管单频单系统（SF-SS），用于多GNSS的卫星选择和基于多GNSS的部分歧义度解决方案（PAR）可以实现快速定位，但是它们不同的理论基础导致歧义度的不同固定可靠性。因此，我们提供了分析命名系统的歧义解决能力的理论。通过添加卫星观测，可以得出给出原始浮点参数的方差-协方差矩阵变化的方程式。然后，获得在添加观测值之前和之后原始模糊度矢量（OAV）的精度模糊度（ADOP）值之间的关系。接下来是对OAV概率密度函数，整数最小二乘引入区域和基于R比率测试的整数孔径引入区域变化趋势的分析。在精度，基于ADOP和基于R比率测试的歧义固定可靠性方面，分析表明，多重GNSS可以改善部分歧义的估计和验证。此外，与卫星选择和SF-SS相比，PAR是最佳的。基于北斗导航卫星系统（BDS）和基于全球定位系统（GPS）的单周期定位实验表明，基于BDS B1和B1的PAR在ADOP和R比率测试方面均胜过基于GPS L1和L1的PAR基于固定的可靠性。前者的ADOP小于0.14，并且基于R比率测试的接受度和成功率均高达99.64％。最后，