GPS广播星历非整点时刻数据块性能分析

Quality Assessment of Non-integer-hour Data Blocks in GPS Broadcast Ephemeris

实时用户从广播星历获取卫星轨道和钟差,广播星历的质量影响用户的定位精度。本文首先描述了GPS广播星历中非整点时刻数据块的三种出现形式;其次,结合一周GPS星历从轨道和钟差两方面分别对非整点时刻数据块进行分析,结果证明非整点时刻数据块并非粗差数据,且其精度优于整点时刻数据块;最后,针对GPS星历中非整点时刻数据块,给出了使用建议。

GPS broadcast ephemeris provides orbit and clock error for real-time positioning applica- tions, thus any abnormal effect in the broadcast ephemeris could cause significant influence on the po- sitioning solution. Due to firmware anomalies in the GPS satellite and the ground control segments, redundant navigation messages occur at times, i.e. another data block is unexpectedly generated 16 ＊ N （N= 1,2,＂＇,15） seconds prior to the GPST integer hour. These non-integer-hour blocks however have not received much attention in terms of quality assessment. This paper first describes the three types of non-integer-hour data blocks in GPS broadcast ephemeris. An assessment strategy is pro- posed so as to conduct a comparison Between the non-integer-hour and integer-hour data Blocks with respect to the IGS final products. The results indicate that non-integer-hour data blocks are not blun- ders. Such non-integer-hour blocks can even provide better accuracies than corresponding integer-hour data blocks based on one-week GPS broadcast ephemerides. Finally, recommendations about how to utilize the GPS non-integer-block data blocks are provided.