北斗卫星类型间偏差快速改正分析

针对北斗卫星类型间偏差（ISTB）导致载波相位差分高精度定位（RTK）的整周模糊度无法固定问题，本文提出了改进ISTB快速改正方法，在观测量层面仅利用1组不同卫星类型的载波相位差分观测量即可实现ISTB估计与改正，实际应用中较传统方法更具普适性与简易性。该方法的测试结果表明，ISTB值由NH码调制不同引起，不同频点的ISTB值具有不一致性；此外，有无改正ISTB的北斗RTK性能对比反映了ISTB会严重降低整周模糊度固定与RTK定位性能。由此可知，本文方法能够保障现阶段北斗接收机更新换代过程中北斗RTK的高精度与高可靠性能。

Rapid determination of BDS inter-satellite-type bias

Owing to inter-satellite-type bias (ISTB) that affects integer ambiguity resolution of BDS real-time kinematic (RTK), rapid ISTB determination method is proposed. This proposed method employs only one carrier phase differential observation between different satellite types to achieve ISTB estimation and calibration, so that it is more universal and simpler for practical applications than the traditional method. The tested results show that the ISTB is relevant to the NH code modulation and the ISTBs of different BDS frequencies are inconsistent. Besides, by comparing performances of BDS-RTK with and without ISTB calibration, the results reflect that ISTB will seriously reduce BDS-RTK positioning accuracy and integer ambiguity resolution performances. Therefore, the rapid and accurate calibration of ISTB can effectively guarantee the high precision and high reliability of the BDS-RTK at the present stage of BDS receiver update.