中文摘要：

在卫星导航定位系统中,空间信号精度SISA是反映完备性参数的重要指标之一。从SISE与SISA的基本概念出发,描述了SISA的计算算法,根据卫星星钟的不同,选取了不同类型的GPS卫星,并利用IGS精密星历,预报精密星历进行了SISE和SISA的计算,结果表明：IGR星历计算的SISA指标满足系统要求,SISA主要受卫星钟差的精度影响,不同原子钟类型的卫星计算出来的SISA值变化不大。该成果对于卫星导航的完备性监测数据处理具有参考意义。

英文摘要：

In the satellite navigation and positioning system,the accuracy of signal space SISA is one of important parameters that indicated integrity.This article,based on basic concepts of SISE and SISA,introduced the arithmetic of SISA,according to differences of satellite clock,selected different types of GPS satellites,forecast precise ephemeris with IGS precise ephemeris to compute SISE and SISA,results showed that：SISA computed by IGR ephemeris met requirements of the system,the factor that affected SISA was mostly satellite clocks,the value of SISA computed by different types of satellite atomic clocks changed not too much.The results had a guiding significance for data processing of index for integrity monitoring in the satellite navigation.