The GPS satellite clock bias (SCB) is an obstacle to real time PPP applications because the IGS cannot offer the real time and extrapolation precise SCB at present.

• 但是IGS现在还不能提供实时和外推的精密卫星钟差，GPS卫星钟差仍然是实现PPP技术实时应用的瓶颈问题，制约了实时PPP技术的应用。