“SA”和“AS”技术对GPS精密大地测量影响的实验研究

根据青藏高原ＧＰＳ实测数据,讨论了“ＳＡ”和“ＡＳ”技术对ＧＰＳ精密大地测量的影响。认为“ＳＡ”和“ＡＳ”技术对静态单点定位精度的影响是严重的,不能单纯依赖延长观测时间来提高其精度;它们还将使载波相位测量精度有所下降;对载波相位测量差分法无甚影响,但必须设法获得起算点在ＷＧＳ８４坐标系中具有一定精度的坐标。最后提出了相应的解决途径

EXPERIMENT ON IMPACT OF SELECTIVE AVAILABILITY AND ANTI-SPOOFING ON PRECISE GEODETIC SURVEY WITH GPS

Based on the data of GPS surveying in Qinghai-Xizang plateau, the impact of Selective Availability and Anti-Spoofing on precise geodetic survey with GPS is discussed. The results demonstrate that the impact of "SA" and "AS" on static single positioning is serious. It is impossible to increase the accuracy by extending the time of measurement only. They reduce the accuracy of measurement of carrier phase,but not effect on the differential measurement of carrier phase as long as there are origin coordinates with suitable accuracy in the WGS84 system. Finally some ways to deal with the impact of Selective Availability and Anti-spoofing are presented.