Performance Testing of Time Comparison using GPS Smoothed P3 Code and IGS Ephemerides

In this paper, the characteristics of time transfer using GPS smoothed P3 code with IGS precise ephemerides are studied. The carrier-smoothed P3 code is used to compute the timing information and IGS precise ephemerides are adopted to calculate the satellites´ coordinates. The two modifications have different effects. The IGS precise ephemerides are more accurate than the broadcast ephemerides; hence, the REFGPS results computing from different satellites are more accurate. On the other hand, since the carrier-smoothed P3 code has smaller noise level than P3 code does, the differences of REFGPS between laboratories are more accurate. The time comparison between laboratories are also processed to show our program is sound and effective