中文摘要：

导航系统可用性是系统在某一区域内提供可用导航服务能力的重要指标。通过对实验区域（0°N—60°N,60°E—150°E）内1°×1°格网点24 h中截止角对导航系统PDOP可用性的影响和5°截止角下卫星可见性、系统可用性的详细分析,得出了我国现阶段北斗卫星导航系统在时间、空间上可用性的分布规律。初步分析表明,取截止角为5°时系统可用性〉98%,实验区域内,卫星可见性和可用性已能够较好满足我国以及邻近区域内的定位和导航需求。

英文摘要：

The availability of navigation system is a major indicator of service capability for a certain area .This paper involves a detailed analysis on masking angle influence on PDOP system availability, satellite visibility and PDOP system availability under 5°masking angle in the test field within 24 hours （60°E-150°E,0°N-60°N, 1°＆#215;1°net）.The distribution regularities of availability in time and space for BDS at the present stage are obtained.The preliminary analysis shows that PDOP availability under 5°masking angle is 98% better and the BDS can provide ideal visibility of PDOP value and availability for the users of our and neighbour countries .