The tight combination model improves the positioning accuracy of the Global Navigation Satellite System (GNSS) in complex environments by increasing the redundancy of observation. However, the ambiguity cannot be calculated directly because of the correlation between it and the phase difference inter-system bias (DISB) in the model. This paper proposes a method of DISB estimation based on the principle of maximum ratio. From the data analysis, for the standard deviation of code DISB, the improvement of the method can up to 0·179 m with the poor quality data. In addition, compared to the parameter combination method, the standard deviation of all the phase DISB was deceased with the method in the paper. About the phase DISB of GPS L1/Galileo E1, the standard deviation decreased from 0·014/0·022/0·009/0·051 cycles to 0·006/0·015/0·004/0·029 cycles of four baselines, which represents the improvement of 57·14/31·82/55·56/43·14%. About the phase DISB of GPS L1/BDS B1, the standard deviation decreased from 0·014/0·061/0·010/0·052 cycles to 0·002/0·005/0·009/0·004 cycles of four baselines, which represents the improvement of 85·71/91·80/10·00/92·31%.

中文翻译：

---

基于最大比原理的差分系统间偏差估计

紧密组合模型通过增加观测冗余度，提高了复杂环境下全球导航卫星系统（GNSS）的定位精度。然而，由于模糊度与模型中的相位差系统间偏差（DISB）之间存在相关性，因此无法直接计算模糊度。本文提出了一种基于最大比原理的DISB估计方法。从数据分析来看，对于代码DISB的标准差，在数据质量较差的情况下，该方法的改进可以达到0·179 m。此外，与参数组合法相比，本文方法降低了所有相位DISB的标准差。关于 GPS L1/Galileo E1 的相位 DISB，四个基线的标准差从0·014/0·022/0·009/0·051个周期下降到0·006/0·015/0·004/0·029个周期，代表57·14个周期的提高/31·82/55·56/43·14%。GPS L1/BDS B1的相位DISB，标准差从0·014/0·061/0·010/0·052个周期下降到0·002/0·005/0·009/0·004个周期四个基线，代表提高了 85·71/91·80/10·00/92·31%。