Precision Analysis on Orbit and Clock of GPS Satellites Broadcast Ephemeris

We pointd out several key issues,which should be well resolved before the precision analysis of GPS broadcast ephemeris.Statistical analysis of both the orbital and clock accuracy were presented with a test of a period of two weeks,mainly from the aspect of satellite itself.The orbital accuracy reached 2-3 m,and the clock precision reached about 10 nanoseconds.In addition,The precision varies from satellites to satellites.Satellites of Block IIR were superior to that of Block IIA,while rubidium clocks were better than cesium clocks,especially in the acpect of stability.