摘要
BDS(BeiDou satellite navigation System,北斗卫星导航系统)的MEO/IGSO(Medium Earth Orbit/Inclined Geosynchronous Satellite Orbit,中圆地球轨道/倾斜地球同步轨道)卫星在D1导航电文上调制了NH(Neumann-Hoffman,奈曼-霍夫曼)二次编码,而在GEO(Geostationary Earth Orbit,地球静止轨道)卫星上未使用。利用北斗MEO/IGSO和GEO卫星进行差分定位时,采用不同NH码符号映射规则的接收机之间会出现半周载波相位偏差的问题,严重影响RTK(Real-Time Kinematic,实时动态差分)应用。通过分析半周载波相位偏差的形成机理,从单差、双差、三差应用角度分别研究了半周载波相位偏差的影响。分析结果表明,接收机NH码符号映射规则与卫星不一致时,接收机直接用乘法器对NH码解调将存在反相,也即引入了半周载波相位偏差;在满足特定条件下,单差和双差应用时会存在半周载波相位偏差的问题;三差应用时不存在半周载波相位偏差的问题。最后,提出了需在北斗接口控制文件中明确卫星NH码调制或映射规则的修订建议。
The D1 NAV messages broadcasted by the Medium Earth Orbit/Inclined Geosynchronous Satellite Orbit （MEO/IGSO） satellites of BeiDou satellite navigation System （BDS） are modulated by a Neumann-Hoffman （NH） secondary code, while the D2 NAV messages broadcasted by the Geostationary Earth Orbit （GEO） satellites do not. In the case of differential positioning between BDS MEO/IGSO and GEO satellites＊ half-cycle carrier phase bias may be induced between receivers that take different NH sign conventions, which results in a failure when perform-ing Real-Time Kinematic （RTK） positioning. Formation mechanism of the half-cycle carrier phase bias is analyzed, and its impact on single, double , and triple difference is discussed. Theoretical analysis shows that the NH sign con-vention difference between BDS satellites and receivers brings a phase opposition, i. e. ,half a cycle phase bias,after the NH code being demodulated by using multiplication in receivers, only under several specified conditions, half-cycle carrier phase bias presents in single difference and/or double difference model. There is no half-cycle carrier phase bias problem in triple difference model. Finally, it is proposed that the NH code modulation rule or sign con-vention needs to be explicitly indicated in the revised Interface Control Document （ICD） of BDS.
出处
《飞行器测控学报》
CSCD
2016年第6期463-469,共7页
Journal of Spacecraft TT&C Technology
