GEO卫星轨道机动对BDS NPA阶段的RAIM可用性影响分析

统计分析各GEO卫星轨道机动对亚太区域NPA（non-precision approach）阶段的RAIM（receiver autonomous integrity monitoring）可用性影响。结果表明，GEO卫星在07∶00～08∶00和15∶00～16∶00对系统的可用性影响最大，但各卫星影响时段不同；GEO卫星C04卫星14∶00～23∶00和C05卫星00∶00～05∶00的调控时段使得系统可用性低于99.9%，分析原因可知，其主要受两颗卫星的定点位置和MEO卫星的回归周期影响。另外，为了揭示新启用的IGSO C13卫星对BDS系统在服务区域可用性的改善情况，对比分析了新IGSO C13卫星启用前后对BDS系统在亚太区域内可用性影响情况发现，C13卫星的运行使得BDS系统在服务区的可用性平均提高0.05%，达到99.99%。

Analysis of BDS RAIM Availability in NPA Considering GEO Satellite Orbit Maneuver

The RAIM(receiver autonomous integrity monitoring) availability effect in the Asian-Pacific region at non-precision approach(NPA) caused by each GEO satellite is counted using the RAIM availabilityadjustment method. Results show that the maximum availability differences affected by GEO satellites are 07∶00~08∶00 and 15∶00~16∶00, but the influence of each GEO is different. The orbit control periods of 14∶00~23∶00 for GEO C04 and 00∶00~05∶00 for GEO C05 make system availability lower than 99.9%, mainly caused by the designated position of the two GEO satellites and the regression cycle of MEO satellites. In addition, in order to reveal the availability improved by the new C13, which is an initial operational capability IGSO satellite, availability before and after having the BDS C13 satellite are obtained. It can be seen that the average RAIM availability reaches 99.99% after enabling the C13 satellite.